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<div class="os1">9.5 数据容器的迭代器 </div>
<br>
本节列举数据容器对应的迭代器，Java 风格迭代器是单独的类，STL 风格的迭代器是数据容器类自己内嵌的，容器类的迭代器用法很相似。
QList、QQueue、QVector、QStack 等容器经常根据序号使用中括号运算符遍历访问元素，而其他的容器则更多地使用迭代器进行遍历。 <br>
<br>
<div class="os2">9.5.1 STL 风格迭代器 </div>
<br>
本章所有容器类型都有 STL 风格的迭代器，内嵌到类型内部，每个容器类都有只读迭代器和读写迭代器，如下表所示：<br>
<br>
<table class="tabel">
<tbody>
<tr class="d1">
<td style="width: 33%;" align="center"><b>容器</b></td>
<td style="width: 33%;" align="center"><b>只读迭代器</b></td>
<td align="center"><b> 读写迭代器</b></td>
</tr>
<tr>
<td>QList<T>, QQueue<T></td>
<td> QList<T>::const_iterator</td>
<td> QList<T>::iterator </td>
</tr>
<tr class="d1">
<td>QLinkedList<T></td>
<td> QLinkedList<T>::const_iterator</td>
<td> QLinkedList<T>::iterator</td>
</tr>
<tr>
<td style="height: 16px;">QVector<T>, QStack<T></td>
<td> QVector<T>::const_iterator</td>
<td> QVector<T>::iterator </td>
</tr>
<tr class="d1">
<td>QMap<Key, T>, QMultiMap<Key, T></td>
<td> QMap<Key, T>::const_iterator</td>
<td> QMap<Key, T>::iterator</td>
</tr>
<tr>
<td>QHash<Key, T>, QMultiHash<Key, T></td>
<td> QHash<Key, T>::const_iterator</td>
<td style="height: 16px;"> QHash<Key, T>::iterator</td>
</tr>
<tr class="d1">
<td>QSet<T></td>
<td style="height: 16px;"> QSet<T>::const_iterator</td>
<td> QSet<T>::iterator</td>
</tr>
</tbody>
</table>
<br>
每个容器的 STL 风格迭代器函数都是该类的成员函数，STL 迭代器使用方法就像指针，*it 是获取元素值，而 it++ 或 ++it
就像是指向下一个元素的指针。STL 风格迭代器使用代码举例：<br>
<div class="code">QList<QString> list;<br>
list << "A" << "B" << "C" << "D";<br>
<br>
QList<QString>::iterator i;<br>
for (i = list.begin(); i != list.end(); ++i)<br>
*i = (*i).toLower();</div>
上述代码定义了列表 list，里面存储四个大写字母；<br>
然后定义迭代器 i，使用 for 循环进行迭代，i 初始为 list.begin() ，每轮循环将元素字符串转为小写，再赋值给元素本身，完成大写转小写；<br>
注意循环结束的判断是 i != list.end() ，因为 end() 指向不存在的假想末尾，是不能访问的假货，不能对 end() 使用
* 运算符访问元素！<br>
STL 迭代器遍历过程如下图所示：<br>
<center> <img src="images/ch09/ch09-05-01.png" alt="STL"></center>
每轮循环，迭代器都指向元素本身，除了 end() 是假想元素不能访问，其他的都是使用 *it 访问元素本身，如果是 QMap
、QHash及其派生类，那么使用 it.key() 和 it.value() 访问键-值对的内容。<br>
对于存储键-值对的容器，STL 风格迭代器的示例代码如下：<br>
<div class="code"> QMap<int, int> map;<br>
map.insert(1,1);<br>
map.insert(2,4);<br>
map.insert(3,9);<br>
//迭代访问<br>
QMap<int, int>::const_iterator it;<br>
for(it=map.constBegin(); it!=map.constEnd(); ++it)<br>
{<br>
qDebug()<< it.key()
<< it.value();<br>
qDebug()<< *it;<br>
}</div>
it.key() 返回元素的关键字内容，it.value() 返回映射值内容，映射和哈希容器也有 *it 的用法。 *it 等同于 it.value()
映射值。上述代码输出为：<br>
<div class="output">1 1<br>
1<br>
2 4<br>
4<br>
3 9<br>
9</div>
STL 风格迭代器常见运算符使用如下表所示：<br>
<table class="tabel">
<tbody>
<tr class="d1">
<td style="width: 30%;" align="center"><b>表达式</b></td>
<td style="width: 70%;" align="center"><b>行为</b></td>
</tr>
<tr>
<td>*i</td>
<td> 访问元素的数值(映射类元素的 value) </td>
</tr>
<tr class="d1">
<td>++i</td>
<td> 移动到下一个元素，注意该运算符不检查越界，越界就是野指针</td>
</tr>
<tr>
<td>i += n</td>
<td> 移动到后面第 n 个元素，注意该运算符不检查越界，越界就是野指针</td>
</tr>
<tr class="d1">
<td>--i</td>
<td> 移动到前一个元素，注意该运算符不检查越界，越界就是野指针</td>
</tr>
<tr>
<td>i -= n</td>
<td> 移动到前面第 n 个元素，注意该运算符不检查越界，越界就是野指针</td>
</tr>
<tr class="d1">
<td>i - j</td>
<td style="height: 48px;"> 对于顺序容器，计算两个迭代器 i 和 j 位置中间包括元素的个数；<br>
如果 i 是迭代器，j 是 int，返回迭代器 i 往前第 j 个元素迭代器。<br>
对于关联容器，j 不能是迭代器，j 只能是整数int，返回迭代器 i 往前第 j 个元素迭代器。</td>
</tr>
<tr>
<td>i.key() 和 i.value()</td>
<td> 映射类元素的关键字 key 和映射值 value</td>
</tr>
</tbody>
</table>
<br>
--i 、++i 与 i--、i++ 都类似指针的用法，前一对在表达式计算之前增减数值，后一对在表达式计算之后增减数值，通常推荐使用 --i 、++i
，这对操作执行效率稍高一些。<br>
除了从前到后迭代，也可以反过来，从后往前迭代：<br>
<div class="code">QList<QString> list;<br>
list << "A" << "B" << "C" << "D";<br>
<br>
QList<QString>::iterator i = list.end();<br>
while ( i != list.begin() )<br>
{<br>
--i;<br>
*i = (*i).toLower();<br>
}</div>
<span style=" color:#ff0000;"><b>注意迭代器移动时，要自己写代码检查是否越界，运算符功能本身不检查越界，
如果移动越界了，就是野指针访问，可能导致程序异常崩溃。</b> </span> <br>
<br>
使用迭代器时，需要特别注意 Qt 类对象的隐式共享特性，如果使用不当，会产生野指针访问：<br>
<div class="code">
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QVector</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">a</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">b</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">a</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">resize</span><span style=" color:#000000;">(</span><span
style=" color:#000080;">100</span><span style=" color:#000000;">);</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//向量初始化为100个0</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">i</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">指向向量第一个元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QVector</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">a</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">begin</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//隐式共享，b</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">和</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">a</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">指向同一块存储空间</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">b</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">a</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//隐式共享在一个对象发生变化后，为变化的对象分配新空间，并赋值</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">a</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">元素修改后，i</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">迭代器与</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">a</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">无关了！！！</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">i</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">其实指向</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">b</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">首元素，因为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">b</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">没有修改，使用旧的内存空间</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">a</span><span style=" color:#000000;">[</span><span
style=" color:#000080;">0</span><span style=" color:#000000;">]</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">5</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//这时候</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">*i</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">是</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">b</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">开头的数值</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">0</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">b</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">clear</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//清空</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">b，那么迭代器</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">i</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">就属于野指针！！！</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">迭代器的错误示范</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">j</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span
style=" color:#000000;">i</span><span style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//野指针使用，未知结果</span></pre></div>
迭代器 i 原本指向 a 的空间，但是隐式共享特性是谁改变数值，就给谁分配新空间，修改 a[0] 之后，迭代器 i 其实已经处于异常状态，已经与 a 无关了。这时候 i 仍然指向 b，那么一旦 b 清除空间，i 就成了野指针，这是非常危险的，可能导致内存错误，程序异常结束。<br>因此，使用迭代器时，一定要注意使用最新的迭代器赋值，不要用旧的过期的迭代器。<br><b>隐式共享对象元素的增删改都可能导致迭代器失效</b>，如果不清楚状况，那最好的做法是复制一个常量对象，对常量对象使用只读迭代器：<br>
<div class="code">// OK<br>const QList<int> sizes = splitter->sizes();<br>QList<int>::const_iterator i;<br>for (i = sizes.begin(); i != sizes.end(); ++i)<br> ...</div>
如果没有使用隐式共享，只是一个对象一个存储空间，那么可以放心使用迭代器，迭代过程中删除元素应该使用专门的迭代器函数 erase()， erase() 会返回下一个元素迭代器位置，<b>迭代循环过程中一般不要使用 remove()，remove() 可能导致之前的迭代器失效</b>。<br>
在迭代过程正确删除元素的示范代码如下：<br>
<div class="code">QHash<QString, int>::iterator i = hash.begin();<br>while (i != hash.end()) <br>{<br> if (i.key().startsWith("_"))<br> i = hash.erase(i);<br> else<br> ++i;<br>}</div>或者保存旧元素的迭代器，提前移动到下一个元素位置，然后删除旧元素迭代器位置：<br>
<div class="code">QHash<QString, int>::iterator i = hash.begin();<br>while (i != hash.end()) <br>{<br> QHash<QString, int>::iterator prev = i;<br> ++i;<br> if (prev.key().startsWith("_"))<br> hash.erase(prev);<br>}</div><br>下面我们编写一个员工工资的例子，运用迭代器进行查询和遍历操作。<br>我们打开 QtCreator，新建一个 Qt Widgets Application 项目，在新建项目的向导里填写：<br>①项目名称 salary，创建路径 D:\QtProjects\ch09，点击下一步；<br>②套件选择里面选择全部套件，点击下一步；<br>③基类选择 QWidget，点击下一步；<br>④项目管理不修改，点击完成。<br>打开 widget.ui 文件进入图形化编辑界面，构造界面如下图所示：<br>
<center> <img src="images/ch09/ch09-05-02.png" alt="ui" width="800"></center>
界面第一行是“人员工资列表”标签。第二行是一个列表控件 listWidget。<br>第三行是“所有人涨10%”按钮 pushButtonIncrease、“查找张三工资”按钮 pushButtonFindZhang3、“查找工资最高3人”按钮 pushButtonFindTop3；<br>第四行是“查找8K以上员工”按钮 pushButtonFind8K、“删除8K以上员工”按钮 pushButtonDel8K；<br>第三行和第四行使用网格布局器排布，2行3列，最后一个网格空的。<br>最后一行是一个文本浏览器 textBrowser。<br>窗口整体使用垂直布局器，窗口大小 420 * 480 。<br>窗口布局设置好之后，我们依次右击每个按钮，从右键菜单为每个按钮的 clicked() 信号添加槽函数，5 个槽函数添加之后，我们下面开始编辑代码。<br>我们开始编辑 头文件 widget.h 的代码：<br>
<div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;"> </span>WIDGET_H
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#define</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">WIDGET_H</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QWidget></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMultiHash></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMultiMap></span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//可以用于键值对的同步排序</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">namespace</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">:</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">public</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">Q_OBJECT</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">public</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">explicit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QWidget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span>parent<span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">~</span><span style=" font-style:italic; color:#000000;">Widget</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//初始化填充</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">InitSalary</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//工资列表变动时，显示到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateSalaryShow</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">slots</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonIncrease_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindZhang3_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindTop3_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFind8K_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonDel8K_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Ui</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//使用哈希映射保存工资表</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#endif</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">WIDGET_H</span></pre></div>
我们添加 QMultiHash、QMultiMap 的头文件包含，QMultiMap 后面代码用于键值对的同步排序。<br>我们为窗口类添加一个多哈希映射类的对象 m_salary 保存工资信息。<br>我们为窗口类添加两个函数，InitSalary() 函数用于填充成员变量 m_salary，存储工资信息，<br>UpdateSalaryShow() 函数用于在成员变量 m_salary 变动时，更新列表控件显示。其他代码都是自动生成的，包括 5 个槽函数。<br><br>下面我们分块编辑 widget.cpp 源文件，首先是构造函数和两个自定义的函数部分：<br>
<div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"widget.h"</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ui_widget.h"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMessageBox></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QDebug></span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">Widget</span><span style=" color:#000000;">(</span><span
style=" color:#800080;">QWidget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">*</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setupUi</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//初始化工资表</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">InitSalary</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateSalaryShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">Widget</span><span style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#008000;">//初始化填充</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">InitSalary</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span><span style=" color:#008000;">//清空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//添加工资内容</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"张三"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">5000.0</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"张三"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">8000.0</span><span
style=" color:#000000;">);</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//有重名的</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"李四"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">6000.0</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"王五"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">7000.0</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"孙六"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">8000.0</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"赵七"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">6600.0</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"钱八"</span><span style=" color:#000000;">),</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">8800.0</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#008000;">//工资列表变动时，显示到列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">UpdateSalaryShow</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//清空旧的内容</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">listWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//只读迭代器遍历</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">const_iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">constBegin</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">!=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">constEnd</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">++</span><span
style=" color:#000000;">it</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strLine</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"\t%1"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">listWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">addItem</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strLine</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//完成</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
构造函数里面，调用 InitSalary() 初始化工资成员变量；调用 UpdateSalaryShow() 更新列表控件显示。<br>在 InitSalary() 函数内部，先清空旧的对象内容，然后简单调用 m_salary.insert() 添加人名和工资数值，人名是有重复的，因此我们使用多哈希映射类型的成员变量。<br>在 UpdateSalaryShow() 函数内部，先清空列表控件里旧的内容，然后使用只读迭代器，遍历 m_salary 内容，将每个元素的人名和工资构造一行文本，根据文本添加一个列表控件条目，显示到列表控件。<br>注意 m_salary.constEnd() 要使用不等于判断，在 it 指向末尾虚假节点时停止迭代，因为末尾虚假节点不能访问，必须终止。<br><br>
接下里我们编辑“所有人涨10%”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//让所有人涨工资</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">10%</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonIncrease_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读写迭代器遍历</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">begin</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">!=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">end</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">++</span><span style=" color:#000000;">it</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读写迭代器</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">it.value()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">返回可以读写的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">value</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">引用，可以作为左值写入</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">1.1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//注意</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">it.key()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">永远是只读引用，不能修改key，映射的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">只能删除或添加，不能直接修改</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateSalaryShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"所有人涨工资</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">10%</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">完毕。"</span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
定义可以读写的迭代器 it，然后循环遍历 m_salary 所有元素，获取每个元素的 value() ，注意读写迭代器返回的 it.value() 是一个可以读写的值引用，<br>it.value() *= 1.1;<br> 这句代码就是能够直接修改元素的 value 值，变为原来的 1.1 倍，就是涨工资 10% ，处理每个元素后，迭代器指向末尾的 m_salary.end()，结束循环。<br>因为 m_salary 内容发生变化，因此我们调用 UpdateSalaryShow() 更新列表控件，然后显示信息字符串到文本浏览框。 <br><br>然后我们编辑“查找张三工资”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//查找所有叫张三的人工资</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonFindZhang3_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//张三有重名，找到第一个张三</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">const_iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_salary</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">find</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"张三"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//信息字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"查找张三结果：\r\n"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//查找多个张三</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_salary</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">constEnd</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"张三"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//连续的多个张三都显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">工资：</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">value</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">++</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//继续找下一个</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//人名不等于张三</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">break</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//遍历到</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">不是张三的位置，不需要再查找</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
定义一个只读迭代器 it，调用 m_salary.find() 找到第一个 "张三" 元素的迭代器位置，构造信息字符串 strInfo；<br>由于多哈希映射可能存在多个 "张三" 元素，因此我们通过循环找出多个 "张三" 元素：<br>如果 it.key() 是等于 tr("张三") ，那么为信息字符串增加一行，显示当前 "张三" 元素及其工资数额，迭代器向后移动；<br>直到遇到下一个元素的名字不等于 tr("张三") ，那么结束循环。<br>查询完成后，我们显示信息字符串到文本浏览框。<br>关键字相同时，键值对总是存储在临近的连续位置，因为计算的哈希表位置一样，find() 函数返回第一个匹配的元素迭代器位置。<br>
<br>下面我们编辑“查找工资最高3人”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//查找工资前三的人</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonFindTop3_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//检查员工人数，如果不超过三个人，就不处理</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">count</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">3</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"不超过三个人，不需要查询。"</span><span style=" color:#000000;">));</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//遍历哈希对象，然后创建工资到人名的QMultiMap映射对象</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//哈希对象迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">const_iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//工资到人名的反向映射</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiMap</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">double</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">mapOrder</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//迭代处理</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">constBegin</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">!=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">constEnd</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">++</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">mapOrder</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">(),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span><span style=" color:#008000;">//反向映射</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//QMultiMap</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">和</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">QMap</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">插入节点时，会自动按照</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">值排序，从小到大排序</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"工资前三的员工：\r\n"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiMap</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">double</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">const_iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">itMap</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">itMap</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">mapOrder</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">constEnd</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//注意不能访问</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">end</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">虚假节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//查找最后三个即可</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">int</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">i</span><span style=" color:#000000;">=</span><span style=" color:#000080;">0</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span
style=" color:#000000;"><</span><span style=" color:#000080;">3</span><span style=" color:#000000;">;</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">i</span><span style=" color:#000000;">++)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">--</span><span
style=" color:#000000;">itMap</span><span style=" color:#000000;">;</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//开头</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">--，会跳过</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">end</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">虚假节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">itMap</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">value</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">工资：%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">itMap</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
函数开头计算一下 m_salary 元素个数，如果不超过三个，那么没必要计算，直接显示信息字符串到文本浏览框，返回。<br>对应 4 个及以上的情况，执行后续操作。<br>我们定义只读迭代器 it，定义多映射类对象 mapOrder；<br>遍历 m_salary 对象每个元素，将工资作为 key，将人名作为 value，旧的 key-value 互换了，添加给 mapOrder，<br>这样 mapOrder 就会以工资数值为关键字来排序，元素的映射值为人名，与工资数额同步排序。<br>mapOrder 的元素添加完成后，排序也就自动完成了，按照工资从小到大排列，我们只需要读取排在最后的三个，就是工资最高的三个人。<br>后续我们就定义信息字符串 strInfo，然后定义只读迭代器 itMap，从迭代器末尾 constEnd() 开始迭代：<br>每轮循环开始时调用 --itMap ，这样就能跳过末尾的虚假节点，进入真实的最后元素，读取 key 工资和 value 人名，添加到信息字符串，<br>最后显示信息字符串到文本显示框。<br>
<br>接下来我们编辑“查找8K以上员工”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//查找</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">8K</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">以上的员工</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonFind8K_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//哈希对象迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">const_iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//信息字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"查找8K以上工资的员工：\r\n"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">cbegin</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">!=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">cend</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">++</span><span style=" color:#000000;">it</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">>=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">8000</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">8K</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">以上的</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">工资：%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">value</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
我们定义只读迭代器 it ，定义信息字符串 strInfo；<br>然后循环遍历 m_salary 的每个元素，检查元素的 value() 是否达到 8000 以上，如果是 8000 以上，那么根据关键字和映射值构造字符串添加到 strInfo；<br>遍历结束后显示信息串到文本浏览框。<br><br>最后我们编辑“删除8K以上员工”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//删除</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">8K</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">以上员工</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonDel8K_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读写迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiHash</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">double</span><span
style=" color:#000000;">>::</span><span style=" color:#800080;">iterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//信息字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"删除8K以上工资的员工：\r\n"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">for</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">begin</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">!=</span><span style=" color:#800000;">m_salary</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">end</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">NULL</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">>=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">8000</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">8K</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">以上的</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">工资：%1\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">value</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//删除迭代器指向的元素，注意旧的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">it</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">删除了不可用</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//必须用</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">erase()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">返回值作为后面元素的新迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_salary</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">erase</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//不删除，直接下一个</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">++</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新列表控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateSalaryShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示信息字符串</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
我们定义读写的迭代器 it，定义信息字符串 strInfo；<br>然后从 m_salary.begin() 开始遍历，注意 for() 小括号里面第三段是 NULL，这里面不进行迭代器移动，因为删除元素操作特殊，不能简单在 for 小括号里移动迭代器；<br>我们判断超过 8000 工资的元素，构造字符串添加到 strInfo，然后调用 m_salary.erase( it ) 删除当前元素，并将 m_salary.erase( it ) 返回值作为新的迭代器存到 it，<br>因为删除元素后，旧的迭代器失效，不能再使用，必须用 erase() 返回的下一个元素迭代器赋值给 it，进行下一轮循环；<br>如果循环时 it 指向元素的工资不够 8000，那么我们才调用 ++it 移动到下一个元素进行下一轮循环。<br>迭代完成之后，我们调用 UpdateSalaryShow() 更新列表控件，并显示信息字符串到文本浏览框。<br>
例子代码讲解到这，我们生成项目，运行例子，我们首先点击“查找工资最高3人”按钮，可以看到如下结果：<br>
<center> <img src="images/ch09/ch09-05-03.png" alt="run1"></center>
查到了工资最高的三个人名单和工资金额，然后我们点击“删除8K以上员工”按钮，运行结果如下：<br>
<center> <img src="images/ch09/ch09-05-04.png" alt="run2"></center>
在上半部分的列表框可以看到删除了 8000 以上工资的员工，信息显示到下半部分的文本浏览框了。其他按钮功能请读者自行测试。下面我们讲解 Java 风格迭代器内容。<br><br>
<div class="os2">9.5.2 Java 风格迭代器 </div>
<br>
除了STL 风格的迭代器，Qt 还为容器类定制了 Java 风格的迭代器，函数与 Java 语言的迭代器类相似。Java 语言通常不使用指针，所以不会用 *it 这种语法，都是用函数来进行元素访问。Java 风格的迭代器使用单独的类来封装，分为只读迭代器类和读写迭代器类，列举如下：<br>
<br>
<table class="tabel">
<tbody>
<tr class="d1">
<td style="width: 33%;" align="center"><b>容器</b></td>
<td style="width: 33%;" align="center"><b>只读迭代器</b></td>
<td align="center"><b> 读写迭代器</b></td>
</tr>
<tr>
<td>QList<T>, QQueue<T></td>
<td> QListIterator<T></td>
<td> QMutableListIterator<T></td>
</tr>
<tr class="d1">
<td>QLinkedList<T></td>
<td> QLinkedListIterator<T></td>
<td> QMutableLinkedListIterator<T></td>
</tr>
<tr>
<td style="height: 16px;">QVector<T>, QStack<T></td>
<td> QVectorIterator<T></td>
<td> QMutableVectorIterator<T></td>
</tr>
<tr class="d1">
<td>QMap<Key, T>, QMultiMap<Key, T></td>
<td> QMapIterator<Key, T></td>
<td> QMutableMapIterator<Key, T></td>
</tr>
<tr>
<td>QHash<Key, T>, QMultiHash<Key, T></td>
<td> QHashIterator<Key, T></td>
<td style="height: 16px;"> QMutableHashIterator<Key, T></td>
</tr>
<tr class="d1">
<td>QSet<T></td>
<td style="height: 16px;"> QSetIterator<T></td>
<td> QMutableSetIterator<T></td>
</tr>
</tbody>
</table>
<br>
所有支持读写的迭代器类都带 Mutable 前缀，表示元素可变的迭代器。因为 Java 不使用指针，所以 Java 迭代器并不会直接指向元素，而像是指向元素前面或后面的狭缝，如下图所示：<br>
<center> <img src="images/ch09/ch09-05-05.png" alt="java"></center>
Java 风格迭代器的示例代码如下：<br>
<div class="code">QList<QString> list;<br>list << "A" << "B" << "C" << "D";<br><br>QListIterator<QString> i(list);<br>while (i.hasNext())<br> qDebug() << i.next();</div>
QListIterator<QString> i(list) 这句代码是根据列表对象定义一个 Java 风格迭代器，这时候迭代器 i 指向首元素前面的狭缝，<br>使用 i.next() 函数，会返回首元素，并且移动到迭代器的下一个狭缝。不存在 *i 或者 ++i 之类的用法， i.next() 函数把取值和移动位置两件事都办了。<br>判断结尾的方式是 i.hasNext() ，如果有下一个狭缝位置，说明没到结尾；否则没有下一个狭缝位置，循环结束。<br>循环结束时迭代器指向末尾元素后面的狭缝。<br>
<br>如果希望倒过来，从末尾开始迭代，那么使用下面代码：<br>
<div class="code">QListIterator<QString> i(list);<br>i.toBack();<br>while (i.hasPrevious())<br> qDebug() << i.previous();</div>
i.toBack() 就是移动到末尾元素后面的狭缝，然后使用 i.previous() 函数，访问元素并向前移动；<br>循环移动直到开头元素前面的狭缝，开头元素前面的狭缝就没有更靠前的狭缝，循环结束。<br><br>正向遍历和反向遍历的过程是左右对称的，访问的元素总是 i.next() 函数或者 i.previous() 函数刚刚滑过的元素，如下图所示：<br>
<center> <img src="images/ch09/ch09-05-06.png" alt="java2"></center>
对于只读迭代器，访问函数如下表所示：<br><br>
<table class="tabel">
<tbody>
<tr class="d1">
<td style="width: 30%;" align="center"><b>函数</b></td>
<td style="width: 70%;" align="center"><b>行为</b></td>
</tr>
<tr>
<td>void toFront()</td>
<td> 移动到首元素前面的狭缝</td>
</tr>
<tr class="d1">
<td>void toBack()</td>
<td> 移动到尾元素后面的狭缝</td>
</tr>
<tr>
<td>bool hasNext() const</td>
<td> 如果位置不是尾元素后面的狭缝，返回 true</td>
</tr>
<tr class="d1">
<td>Item next()</td>
<td> 向后移动一个狭缝位置，并返回狭缝前面的刚滑过的元素</td>
</tr>
<tr>
<td>Item peekNext() const</td>
<td> 返回狭缝后面的元素，不移动狭缝位置</td>
</tr>
<tr class="d1">
<td>bool hasPrevious() const</td>
<td> 如果不在首元素前面的狭缝位置，返回 true</td>
</tr>
<tr>
<td>Item previous()</td>
<td> 向前移动一个狭缝位置，并返回狭缝后面的刚滑过的元素</td>
</tr>
<tr class="d1">
<td>Item peekPrevious() const</td>
<td> 返回狭缝前面的元素，不移动狭缝。</td>
</tr>
<tr>
<td style="height: 16px;">bool findNext(const T & value)</td>
<td> 从迭代器当前狭缝开始向后查找，如果找到匹配 value 的元素，移动到该元素后面的狭缝（<b>正好滑过该元素</b>），返回 true，否则移动到尾元素后面的狭缝，并返回 false</td>
</tr>
<tr class="d1">
<td>bool findPrevious(const T & value)</td>
<td> 从迭代器当前狭缝开始向前查找，如果找到匹配 value 的元素，移动到该元素前面的狭缝（<b>正好滑过该元素</b>），返回 true，否则移动到首元素前面的狭缝，并返回 false</td>
</tr>
<tr>
<td>const Key & key() const<br>const T & value() const</td>
<td> 映射和哈希映射的迭代器函数，返回关键字和映射值</td>
</tr>
</tbody>
</table>
<br>
<b>使用 Java 风格迭代器，一定要注意“刚滑过的元素”的概念，刚滑过的元素，就是迭代器当前读写的元素。</b><br>
例如对于映射类对象的迭代器，示例代码如下：<br>
<div class="code">
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMap</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">1</span><span style=" color:#000000;">,</span><span
style=" color:#000080;">1</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">2</span><span style=" color:#000000;">,</span><span
style=" color:#000080;">4</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">3</span><span style=" color:#000000;">,</span><span
style=" color:#000080;">9</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//Java</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">风格迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">hasNext</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">next</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">qDebug</span><span
style=" color:#000000;">()<<</span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()<<</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//要从头开始</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">findNext()，如果从末尾开始</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">findNext()那么后面没有任何元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">toFront</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//查找</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">bool</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bRet</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">findNext</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">9</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">bRet</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">qDebug</span><span
style=" color:#000000;">()<<</span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()<<</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">qDebug</span><span
style=" color:#000000;">()<<</span><span style=" color:#008000;">"Can</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">not</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">find."</span><span style=" color:#000000;">;</span></pre></div>
循环迭代时，it.next() 滑到后面一个狭缝，但是 key() 和 value() 访问的是刚滑过的元素。<br>对于 findNext() 函数，注意它是从迭代器当前狭缝开始往后查找元素 value，如果从末尾元素后面的狭缝开始 findNext() ，后面不存在任何元素，所以要在开始之前，调用 it.toFront() 移动到最开头的狭缝，这样才能遍历容器对象查找匹配的元素。<br>注意要检查 findNext() 返回值，如果为 true，那么可以使用 key() 和 value() 访问刚滑过的元素，就是找到的匹配元素，如果返回值为 false，那么迭代器指向末尾元素后面的狭缝，没有找到任何匹配内容。上面代码输出结果如下：<br>
<div class="output">1 1<br>2 4<br>3 9<br>3 9</div>
使用 Java 风格迭代器，也要注意不能出现越界访问，比如 toFront() 是首元素的前面狭缝，这时候不能调用 previous() 和 peekPrevious() 函数；<br>如果处在 toBack() 尾元素的后面狭缝，这时候不能调用 next() 和 peekNext() 函数；越界访问可能导致程序异常崩溃，需要特别注意判断越界条件。<br>
<br>对于支持读写的迭代器 QMutable***Iterator，会额外多出如下函数，用于修改 value 和删除元素：<br><br>
<table class="tabel">
<tbody>
<tr class="d1">
<td style="width: 30%;" align="center"><b>函数</b></td>
<td style="width: 70%;" align="center"><b>行为</b></td>
</tr>
<tr>
<td>void setValue(const T & value)</td>
<td> 针对<b>刚滑过的元素</b>，设置 value 值</td>
</tr>
<tr class="d1">
<td>T & value()</td>
<td> 返回<b>刚滑过的元素</b>的 value 的可读写引用，支持 it.value() += 1024 这种修改数值代码。</td>
</tr>
<tr>
<td>void remove()</td>
<td> 删除<b>刚滑过的元素</b>。</td>
</tr>
</tbody>
</table>
<br>
Java 风格迭代器的所有读写操作都是针对<b>刚滑过的元素</b>，而不管迭代器位置是在元素的前面或后面狭缝。例如下面代码：<br>
<div class="code">
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMap</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">1</span><span style=" color:#000000;">,</span><span
style=" color:#000080;">1</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">2</span><span style=" color:#000000;">,</span><span
style=" color:#000080;">4</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">map</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">3</span><span style=" color:#000000;">,</span><span
style=" color:#000080;">9</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//Java</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">风格读写迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMutableMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#808000;">int</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">map</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">hasNext</span><span style=" color:#000000;">())</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">next</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//滑过一个元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span
style=" color:#008000;">//对刚滑过的元素进行访问和处理</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">remove</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//删除关键字等于映射值的元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">qDebug</span><span
style=" color:#000000;">()<<</span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()<<</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre></div>
上面代码能够准确删除关键字等于映射值的元素，然后打印其他未删除的元素内容，输出如下：<br>
<div class="output">2 4<br>3 9</div>
<br><b>无论对于 STL 风格和 Java 风格迭代器，注意同一时间只能有一个读写迭代器处理容器对象，一个容器对象不能同时使用多个读写迭代器，那样会造成内存访问错乱，程序可能崩溃。如果使用只读迭代器，那么一个容器对象可以使用多个只读迭代器读取内容。</b><br><br>对于关联容器的迭代器可以写入的内容是 value ，关键字 key 是不能直接修改的，只能删除或重新添加。<br>对于 QSet 类，它的 value 其实相当于哈希映射的关键字，QSet 的元素在迭代器中只能读取和删除，而不能赋值修改。<br><br>Java 风格迭代器的内容介绍到这，下面我们学习一个模拟 TCP 连接管理的例子，例子仅使用模拟的 IP 地址和端口号作为数据存在容器里，并不真的进行网络连接。<br>我们打开 QtCreator，新建一个 Qt Widgets Application 项目，在新建项目的向导里填写：<br>①项目名称 tcpmanager，创建路径 D:\QtProjects\ch09，点击下一步；<br>②套件选择里面选择全部套件，点击下一步；<br>③基类选择 QWidget，点击下一步；<br>④项目管理不修改，点击完成。<br>
打开 widget.ui 文件进入图形化编辑界面，构造界面如下图所示：<br>
<center> <img src="images/ch09/ch09-05-07.png" alt="UI" width="800"></center>
界面第一行是一个“TCP连接列表”标签。第二行是一个树形控件 treeWidget。<br>第三行是“IP”标签、单行编辑器 lineEditIP、“端口”标签、旋钮编辑框 spinBoxPort，设置旋钮编辑框属性 sizePolicy 水平策略为 Expanding，第三行控件按照水平布局器排布。<br>第四行是三个按钮：“添加TCP连接”按钮 pushButtonAddTCP、“删除匹配IP连接”按钮 pushButtonDelIP、“删除匹配端口连接”按钮 pushButtonDelPort，这三个按钮按照水平布局器排布。<br>第五行是两个按钮：“查找1024以下小端口连接”按钮 pushButtonFindBelow1024、“给小端口号增加1024”按钮 pushButtonPlus1024，第五行按钮按照水平布局器排布。<br>最后一行是文本浏览框 textBrowser。窗口整体按照垂直布局器排列，窗口大小 440 * 560 。<br>界面编辑好之后，我们依次右击五个按钮，在右键菜单为每个按钮添加 clicked() 信号对应的槽函数。<br>
下面我们编辑头文件 widget.h 的内容：<br>
<div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;"> </span>WIDGET_H
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#define</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">WIDGET_H</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QWidget></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMultiMap></span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//保存IP和端口映射</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">namespace</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">class</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Widget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">:</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">public</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">Q_OBJECT</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">public</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">explicit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QWidget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span>parent<span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">~</span><span style=" font-style:italic; color:#000000;">Widget</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//初始化填充</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">InitTCPLinks</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新树形控件的显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">slots</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonAddTCP_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonDelIP_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonDelPort_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonFindBelow1024_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">on_pushButtonPlus1024_clicked</span><span
style=" color:#000000;">();</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">private</span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Ui</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//保存IP和端口信息</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMultiMap</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">;</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">};</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#endif</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">WIDGET_H</span></pre></div>
我们添加 QMultiMap 头文件包含，用于保存IP端口号信息。<br>窗口类添加多映射成员变量 m_tcplinks，关键字是 IP 地址字符串，映射值是端口号。<br>然后手动添加两个函数，InitTCPLinks() 用于初始化填充成员变量 m_tcplinks，UpdateTreeShow() 是将 m_tcplinks 内容显示到界面的树形控件，每次IP端口发生变化时，就调用该函数更新树形控件显示。其他代码都是自动生成的，包含五个按钮对应的槽函数。<br><br>
接下来我们分块编辑 widget.cpp 源文件内容，首先是开头构造函数内容：<br>
<div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"widget.h"</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"ui_widget.h"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMessageBox></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QDebug></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMapIterator></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QMutableMapIterator></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QTreeWidgetItem></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QRegExp></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QRegExpValidator></span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">Widget</span><span style=" color:#000000;">(</span><span
style=" color:#800080;">QWidget</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">*</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">:</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QWidget</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">parent</span><span
style=" color:#000000;">),</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">Ui</span><span style=" color:#000000;">::</span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setupUi</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">);</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置树形控件只有</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">列</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">treeWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setColumnCount</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">treeWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">header</span><span
style=" color:#000000;">()-></span><span style=" color:#000000;">setHidden</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">true</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//隐藏头部，未使用</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IP编辑框</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IPv4</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">正则表达式，注意</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"\\"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">就是一个反斜杠字符</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">re</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}"</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//新建正则表达式验证器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExpValidator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">reVali</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QRegExpValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">re</span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置给</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">lineEditIP</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditIP</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setValidator</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">reVali</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">lineEditIP</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.1"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//默认值</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//设置端口范围</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">spinBoxPort</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setRange</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">0</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">65535</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">spinBoxPort</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setValue</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">1500</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//默认值</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//初始化填充连接信息</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">InitTCPLinks</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新树形控件的显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">Widget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">Widget</span><span style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#008000;">//初始化填充</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">InitTCPLinks</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//清空旧的</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.1"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">80</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.1"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">443</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.2"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">20</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.2"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">21</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.3"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">80</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.3"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">443</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"192.168.1.3"</span><span
style=" color:#000000;">),</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">3306</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
文件开头添加了多个类型头文件包含，然后在窗口的构造函数里，我们设置树形控件 ui->treeWidget 只有 1 列信息，并设置树头标题部分隐藏，因为这部分没使用；<br>然后定义正则表达式 re 和正则表达式验证器 reVali ，将验证器设置给单行编辑器 ui->lineEditIP，这样限定输入合法的 IPv4 地址；<br>设置单行编辑器初始地址字符串为 "192.168.1.1"；<br>设置旋钮编辑器的数值范围 0 ~ 65535，就是端口号范围，然后设置初始端口号数值为 1500 ；<br>构造函数最后调用 InitTCPLinks() 填充初始的 IP端口号信息，并调用 UpdateTreeShow() 将IP端口映射对象的信息显示到树形控件。<br>InitTCPLinks() 函数内部比较简单，清空旧的内容，然后添加了 7 个连接元素给 m_tcplinks 对象。<br><br>
下面我们来编辑 UpdateTreeShow() 函数内容，以 IP 地址为顶级树形节点，将所属端口号作为 IP 地址节点的子节点显示。<br>
<div class="code"><span style=" color:#008000;">//更新树形控件的显示</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">treeWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//清空旧的</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//定义迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//保存迭代中旧的IP</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strOldIP</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//保存旧的顶级IP节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QTreeWidgetItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">pOldTopItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">NULL</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//端口号节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QTreeWidgetItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">pPortItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">NULL</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//迭代遍历</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">hasNext</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">next</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//滑过一个元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取滑过元素的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">和端口</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nPort</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strOldIP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//新的主机IP，建立顶级IP节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pOldTopItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QTreeWidgetItem</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pOldTopItem</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">0</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">treeWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">addTopLevelItem</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pOldTopItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//添加端口号为子节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pPortItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QTreeWidgetItem</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pPortItem</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">0</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"%1"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#000000;">nPort</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pOldTopItem</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">addChild</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pPortItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新旧的IP</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strOldIP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strIP</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//现在元素IP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">与</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">上一个元素IP一样</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//添加</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">pOldTopItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">子节点</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pPortItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#808000;">new</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QTreeWidgetItem</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pPortItem</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000080;">0</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"%1"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#000000;">nPort</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pOldTopItem</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">addChild</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">pPortItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span><span style=" color:#008000;">//</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">end</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">while</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//遍历结束，树形控件条目添加完成</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">treeWidget</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">expandAll</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//全部展开</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
该函数先清空旧的树形控件内容，然后定义只读迭代器 it，用于遍历 m_tcplinks 对象；<br>定义字符串 strOldIP 保存迭代过程中的旧 IP 字符串，只要 IP 字符串不变，那就将同主机 IP 的端口设置到一起作为子节点。<br>定义 pOldTopItem 保存同 IP 的顶级树形节点，定义 pPortItem 保存端口号子节点。<br>下面开始循环迭代，循环里面内容：<br>先调用 it.next() 滑过一个元素，刚滑过的元素就是我们要访问的元素；<br>获取刚滑过元素的 IP 和端口到 strIP、nPort 变量；<br> 比较当前 strIP 与旧的 strOldIP 是否相等，如果不相等，说明遇到新的主机 IP，那么我们新建树形条目，存到 pOldTopItem，设置文本为 strIP，并设置为树形控件新的顶级条目；然后为这个顶级条目新建一个子条目 pPortItem，子条目内容就是该主机 IP 的端口号；然后将新的主机 IP 地址存到 strOldIP，用于下轮循环比较；<br> 如果当前循环的 strIP 等于 strOldIP，那说明还是同一个主机 IP 的端口，那么直接新建一个条目 pPortItem ，内容是端口号，添加为顶级条目 pOldTopItem 的子条目。<br>循环结束后，设置树形控件展开所有子节点，方便显示所有的 IP 和端口号。<br><br>
下面我们编辑 “添加TCP连接”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//添加一个连接</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonAddTCP_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">和端口</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditIP</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"IP为空。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//IP为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//端口</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nPort</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">spinBoxPort</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">value</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//检查是否已存在相同的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IP和端口</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">contains</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nPort</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"该IP端口的连接已存在，IP和端口不能同时重复。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//不重复的连接，添加</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">insert</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nPort</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"添加TCP连接完成。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新树形控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
我们先获取 IP 地址字符串 strIP ，如果为空就不处理，如果非空，进行后续处理；<br>获取端口号存到 nPort ，判断容器对象 m_tcplinks 是否已经包含该 IP 和端口的连接，如果已存在了，那么不重复添加，返回；<br>如果没有包含该 IP 和端口，那么调用 m_tcplinks.insert( strIP, nPort ) 插入新元素，保存新的连接；<br>显示信息字符串，表示添加TCP连接完成，并更新树形控件。<br><br>
接下来我们编辑“删除匹配IP连接”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//删除匹配IP的连接</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonDelIP_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">IP</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">ui</span><span style=" color:#000000;">-></span><span
style=" color:#800000;">lineEditIP</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strIP</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"IP为空。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">return</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//IP为空</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//删除计数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nDelCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//使用迭代器查找</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMutableMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//循环查找</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">hasNext</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">next</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//滑过一个元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span style=" color:#000000;">()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">==</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strIP</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//检查滑过元素的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//删除刚找到的滑过元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">remove</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nDelCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//更新删除计数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//判断</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nDelCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"没有匹配的IP。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已删除匹配IP的连接个数：%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">。"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">nDelCount</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新树形控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
我们先获取 IP 地址字符串，如果非空才进行后面的操作；<br>定义删除计数 nDelCount，定义 m_tcplinks 对象的读写迭代器 it；<br>使用 while 循环遍历容器对象每个元素，在循环内部：<br> 先使用 it.next() 滑过一个元素，这个滑过的元素就是要访问的内容；<br> 我们判断滑过元素的 key() ，如果等于 strIP，那么找到匹配的元素，调用 it.remove() 删除刚滑过的元素，并让删除计数加一，进入下轮循环；<br> 如果 key() 不等于 strIP，不处理，直接进入下轮循环。<br>循环结束后，我们判断 nDelCount 删除计数，如果小于 1 ，说明没有匹配的IP，显示信息字符串，不需要更新树形控件；<br>如果 nDelCount 达到 1 以上，那么 显示信息串，删除了 nDelCount 个数的连接，并更新树形控件。<br><br>
接下来我们编辑 “删除匹配端口连接”按钮对应的槽函数内容：<br>
<div class="code"><span style=" color:#008000;">//删除匹配端口的连接</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonDelPort_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//获取端口号</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">const</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">nFindPort</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">spinBoxPort</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">value</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nDelCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</span><span style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//删除计数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//读写迭代器</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMutableMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//循环迭代</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">toFront</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//从头开始</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//注意</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">Q*MapIterator</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">迭代器的</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">findNext()</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">和</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">findPrevious()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">比较的是</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">value</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">而</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">QMap/QMultiMap</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">容器类的</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">find()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">比较的是</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">key</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">或者</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">key-value</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">对。</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">findNext</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nFindPort</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//端口号是</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">value，可以用迭代器的查找函数</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">remove</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nDelCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#000000;">;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//遍历结束</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nDelCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">1</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"没有匹配的端口。"</span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">else</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">"已删除匹配端口的连接个数：%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">。"</span><span style=" color:#000000;">).</span><span
style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">nDelCount</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新树形控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
我们获取要比较的端口号 nFindPort ，定义删除计数 nDelCount；<br>定义 m_tcplinks 对象的读写迭代器 it，并移动到最前面；<br>然后开始循环迭代，循环判断的条件就是直接调用 it.findNext( nFindPort ) 查找该端口号，<br>如果找到该端口号，删除刚滑过的匹配元素，并让删除计数加一；<br>容器对象如果存在多个 nFindPort 端口，那么 while 循环会依次找出所有的匹配端口号元素并删除；<br>如果没找到，那么说明到了迭代器末尾，结束循环。<br>循环结束后，我们判断删除计数 nDelCount，如果小于 1，那么显示没有匹配的端口；<br>否则显示删除了 nDelCount 个数的连接，并更新树形控件显示。<br><br>
接下来我们编辑“查找1024以下小端口连接”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//找寻</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">1024</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">的端口连接</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonFindBelow1024_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"1024以下端口号的连接：\r\n"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//迭代查找</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">hasNext</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">next</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//滑过一个元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">1024</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">端口：%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
该函数先定义 m_tcplinks 容器对象的只读迭代器，然后定义信息字符串 strInfo；<br>循环遍历容器对象，使用 it.next() 滑过一个元素，然后判断刚滑过元素的 value() ，如果小于等于 1024，说明是要找的元素，根据 IP 和端口号构造字符串添加给 strInfo ；如果端口号大于 1024，跳过不处理，进入下轮循环。<br>循环结束后，显示信息字符串到文本浏览框。<br><br>最后我们编辑“给小端口号增加1024”按钮对应的槽函数：<br>
<div class="code"><span style=" color:#008000;">//为所有的小端口号增加</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">1024</span>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Widget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonPlus1024_clicked</span><span
style=" color:#000000;">()</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QMutableMapIterator</span><span
style=" color:#000000;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">int</span><span
style=" color:#000000;">></span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_tcplinks</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span style=" color:#008000;">"修改旧的1024以下端口号的连接：\r\n"</span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//迭代查找</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">while</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">hasNext</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">next</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//滑过一个元素</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;"><=</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">1024</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">)</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">{</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">key</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">端口：%1</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">\r\n"</span><span
style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span style=" color:#000000;">(</span><span
style=" color:#000000;">it</span><span style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//修改端口号，增加1024</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">setValue</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">it</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">value</span><span
style=" color:#000000;">()</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000080;">1024</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//等同于</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">it.value()</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">+=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">1024;</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">}</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//显示</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">ui</span><span
style=" color:#000000;">-></span><span style=" color:#800000;">textBrowser</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">);</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//更新树形控件</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">UpdateTreeShow</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000000;">}</span></pre></div>
该函数先定义 m_tcplinks 对象的读写迭代器，然后定义信息字符串 strInfo；<br>循环遍历容器对象，首先调用 it.next() 滑过一个元素，然后判断滑过元素的 value() 是否小于等于 1024，<br>如果满足条件，那么根据小端口号节点的IP和端口构造字符串添加给 strInfo ，然后调用 it.setValue() 修改滑过元素的映射值；<br>如果是大于 1024 的端口，那么不处理，直接进入下轮循环。<br>遍历结束后面，显示信息字符串到文本浏览框，并更新树形控件显示。<br>it.setValue( it.value() + 1024 ); 这句代码，也可以替换为 it.value() += 1024;<br>这两句代码执行效果是一样的，读写迭代器 it.value() 可以作为左值，进行赋值修改元素的映射值。<br><br>
例子代码讲解到这，我们生成运行示例，看到如下界面：<br>
<center> <img src="images/ch09/ch09-05-08.png" alt="run1"></center>
可以看到每个端口号都显示为 IP 顶级节点的子节点，方便显示主机 IP 和端口的隶属关系。<br>
然后我们设置端口号为 80，点击“删除匹配端口连接”按钮，查看效果：<br>
<center> <img src="images/ch09/ch09-05-09.png" alt="run2"></center>
我们发现有两个端口号为 80 的连接被删除，说明正好删除了所有匹配端口号的连接。然后我们点击“给小端口号增加1024”按钮，看到端口号数值变化：<br>
<center> <img src="images/ch09/ch09-05-10.png" alt="run3"></center>
程序将四个小端口号的数值，都加上了 1024，然后显示到了树形控件，大于 1024 的端口 3306 没有变化。其他按钮功能请读者自行测试，本节的内容介绍到这，我们下一章节开始新的知识学习，学习能够在界面上包裹多个子控件的控件容器。<br><br><br>
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