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    <div class="os1">11.1 QWidget 多窗口使用</div>
    <br>
    本节介绍基于 QWidget
    自定义的多窗口程序，定制子窗口并弹窗显示，在多窗口之间使用信号和槽机制进行多窗口之间的数据传递。多窗口程序可以采用新建子窗口的方式，也可以集成之前开发的窗口模块
    作为子窗口，本节通过新建和集成两种方式展示子窗口的使用。 <br>
    <br>
    <div class="os2">11.1.1 QWidget 类</div>
    <br>
    QWidget 是用户界面所有控件和窗口的基类，涵盖控件和窗口所有基本的功能，比如界面绘制显示、鼠标键盘事件处理等，本节仅介绍一部分窗口显示常用的功能函
    数。<br>
    （1）构造函数<br>
    <div class="code">QWidget(QWidget * parent = 0, Qt::WindowFlags f = 0)</div>
    参数 parent 如果为默认值 0，也就是 NULL，那么新建的 QWidget 对象就是独立的窗口，独立窗口有自己的标题栏和边框；<br>
    如果指定 parent 为已有的窗口或控件，那么新建的 QWidget 就是子控件，子控件的显示受制于父窗口或父控件。<br>
    本节就是专门讲解 QWidget 独立窗口的工作模式，在新建窗口时，不设置 parent 指针或者设为 NULL。<br>
    Qt::WindowFlags 可以控制 QWidget 对象的多种工作类型，比如作为窗口、对话框、控件、菜单显示等等，通常不需要修改窗口标志位，每个功
    能控件都会自行设置合适的工作类型。<br>
    <br>
    （2）显示与隐藏函数<br>
    我们通过 QtCreator 新建的窗口会有默认的标题栏文本和默认尺寸，可以直接在主窗口调用子窗口的显示函数：<br>
    <div class="code">void QWidget::show()&nbsp;&nbsp; //槽函数，显示窗口<br>
      void QWidget::hide()&nbsp;&nbsp;&nbsp; //槽函数，隐藏窗口<br>
      bool&nbsp;&nbsp;&nbsp; isVisible() const&nbsp; //是否处于显示状态<br>
      virtual void&nbsp;&nbsp;&nbsp; setVisible(bool visible)&nbsp; //控制窗口显示或隐藏</div>
    show() 是显示窗口槽函数，hide() 是隐藏窗口槽函数，可以通过信号和槽的关联方便控制窗口显示状态，setVisible(bool
    visible) 一样可以控制窗口显示或隐藏，参数 true 代表显示， false 代表隐藏。<br>
    通常新的子窗口会显示到主窗口的上层，多个窗口的显示可能出现区域重叠，上层的窗口会遮挡下层窗口显示，例如：<br>
    <center> <img src="images/ch11/ch11-01-01.png" alt="multi01"></center>
    窗口本身是二维显示的，横轴 X， 纵轴 Y，多个窗口的上下层叠加，属于 Z 轴排列，上层的显示会遮挡下层窗口。<br>
    控制窗口在 Z 轴的叠加使用下面两个函数：<br>
    <div class="code">void QWidget::raise()&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      //槽函数，将本窗口置于顶层显示<br>
      void QWidget::lower()&nbsp;&nbsp;&nbsp; //槽函数，将本窗口置于底层显示</div>
    raise() 是将窗口放在本程序所有窗口的 Z 轴最上面显示，lower()&nbsp; 则是放到最底层显示。<br>
    用户鼠标点击也会自动切换窗口的 Z 轴位置，鼠标最新点击的窗口通常优先在 Z 轴顶层显示。<br>
    程序的多个窗口通常同一时刻只有一个窗口处于活跃状态，就是用户鼠标键盘输入的焦点，鼠标点击哪个窗口，哪个窗口自动显示到最顶层，使用下面函数可以
    激活窗口，获 取输入焦点：<br>
    <div class="code">void QWidget::activateWindow()&nbsp;
      //激活本窗口，注意本窗口必须处于显示状态才有用<br>
      bool&nbsp;&nbsp;&nbsp; isActiveWindow() const&nbsp;&nbsp;&nbsp;
      //判断是否为活跃状态</div>
    也可以使用 raise() 激活窗口获取输入焦点，处于顶层显示。<br>
    <br>
    对于窗口，如果用户点击标题栏的关闭按钮 X，或者程序调用关闭函数：<br>
    <div class="code">bool QWidget::close()</div>
    窗口就会被关闭，关闭窗口函数首先会隐藏窗口，然后会触发 QCloseEvent，在这个事件里面可以处理关闭窗口的事务。close()
    函数默认情况下不会销毁窗口，当Qt 图形界面程序的所有窗口被关闭时，程序会自动结束，这时才会销毁所有窗口。子窗口调用 close()
    函数之后，子窗口对象默认情况下仍保留内存空间，还是一直存在的，成员变量和成员函数可以照常使用，可以通过 show() 函数重新显示。<br>
    <br>
    QWidget 窗口标题栏默认有最小化、最大化和关闭按钮，用户点击这些按钮会控制窗口的显示形态，通过函数也可以控制窗口的最大化最小化显示：<br>
    <div class="code">void QWidget::showMinimized()&nbsp; //槽函数，最小化显示<br>
      void QWidget::showMaximized() //槽函数，最大化显示，标题栏和窗口主体都显示，占据桌面最大显示区域<br>
      void QWidget::showNormal()&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; //槽函数，正常尺寸显示<br>
      void QWidget::showFullScreen()&nbsp; //槽函数，全屏显示，标题栏隐藏，将窗口主体铺满屏幕</div>
    &nbsp;程序可以通过函数获取窗口的显示状态，如 isMinimized()、isMaximized()
    、isFullScreen()、isVisible()、isHidden() 等。<br>
    默认情况下，程序的多个窗口之间是显示优先级是平等的（非模态显示），有一种特殊的显示方式，叫模态显示，这种窗口会独占显示焦点，强制显示在最上
    层，不关闭模态窗口，就无法操作底层其他窗口。QWidget 有个特殊属性 windowModality 控制窗口的模态显示：<br>
    <div class="code">Qt::WindowModality&nbsp;&nbsp; &nbsp;windowModality()
      const&nbsp; //获取模态状态<br>
      void&nbsp;&nbsp;&nbsp; setWindowModality(Qt::WindowModality
      windowModality)&nbsp; //设置模态状态<br>
      bool&nbsp;&nbsp;&nbsp; isModal() const&nbsp;&nbsp; //是否为模态窗口</div>
    Qt::WindowModality 枚举类型有三种：<br>
    <br>
    <table class="tabel">
      <tbody>
        <tr class="d1">
          <td style="width: 220px;" align="center"><b>Qt::WindowModality 枚举常量</b></td>
          <td style="width: 160px;" align="center"><b>数值</b></td>
          <td align="center"><b> 描述</b></td>
        </tr>
        <tr>
          <td>Qt::NonModal</td>
          <td> 0 </td>
          <td> 非模态窗口，不会阻塞其他窗口输入。 </td>
        </tr>
        <tr class="d1">
          <td>Qt::WindowModal</td>
          <td> 1</td>
          <td> 窗口级模态，在兄弟级别、父级窗口及祖父以上级别窗口中，阻塞其他窗口，独占输入焦 点。 </td>
        </tr>
        <tr>
          <td>Qt::ApplicationModal</td>
          <td> 2</td>
          <td> 应用程序级模态，在本应用程序所有窗口中，阻塞其他窗口，独占输入焦点。 </td>
        </tr>
      </tbody>
    </table>
    <br>
    模态窗口一般设置为 Qt::ApplicationModal 即可，就是独占本程序的输入焦点，模态窗口不关闭，其他窗口都不能使用。<br>
    设置模态窗口时，要注意先设置模态属性，然后再显示窗口；<br>
    如果窗口已经显示了，再设置模态不会即刻生效，需要调用 hide() 隐藏窗口，然后重新 show() 显示窗口。<br>
    模态窗口显示举例：<br>
    <div class="code">&nbsp;&nbsp;&nbsp;
      pModWnd-&gt;setWindowModality(Qt::ApplicationModal);&nbsp; //模态窗口，会阻塞其他窗口<br>
      &nbsp;&nbsp;&nbsp; pModWnd-&gt;show(); //模态窗口总是显示在最顶层，并且独占输入焦点</div>
    <br>
    非模态窗口显示举例：
    <div class="code">&nbsp;&nbsp;&nbsp; pNormalWnd-&gt;show();&nbsp;
      //普通窗口显示，多个窗口都能操作，不会阻塞其他窗口<br>
      &nbsp;&nbsp;&nbsp; pNormalWnd-&gt;raise();&nbsp;&nbsp; //将窗口置于顶层显示，方便用户操作</div>
    <br>
    （3）标题栏设置函数<br>
    窗口标题栏可以设置文本、图标，标题栏文本也就是窗口名称，方便直接说明窗口功能：<br>
    <div class="code">QString&nbsp;&nbsp; &nbsp;windowTitle()
      const&nbsp;&nbsp;&nbsp; //获取标题栏文本<br>
      void&nbsp;&nbsp;&nbsp; setWindowTitle(const QString &amp;) //设置标题栏文本<br>
      QIcon&nbsp;&nbsp;&nbsp; windowIcon() const&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      //获取标题栏图标<br>
      void&nbsp;&nbsp;&nbsp; setWindowIcon(const QIcon &amp; icon)&nbsp;
      //设置标题栏图标<br>
      QString&nbsp;&nbsp;&nbsp; windowIconText() const&nbsp;&nbsp; //获取图标的文本<br>
      void&nbsp;&nbsp;&nbsp; setWindowIconText(const QString &amp;) //设置图标的文本</div>
    <br>
    （4）窗口尺寸位置设置函数<br>
    用户使用鼠标拉动窗口边框可以改变窗口尺寸，拖动标题栏可以控制窗口位置，通过函数也可以获取或修改窗口尺寸位置，相关函数如下面两个表格所示：<br>
    <br>
    <table class="tabel">
      <tbody>
        <tr class="d1">
          <td style="width: 320px;" align="center"><b>窗口尺寸函数</b></td>
          <td align="center"><b> 描述</b></td>
        </tr>
        <tr>
          <td>QSize&nbsp;&nbsp; &nbsp;size() const</td>
          <td> 获取窗口客户区尺寸。 </td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp; &nbsp;resize(int w, int h)</td>
          <td> 根据宽度高度设置窗口尺寸。 </td>
        </tr>
        <tr>
          <td>void&nbsp;&nbsp; &nbsp;resize(const QSize &amp;)</td>
          <td> 设置窗口尺寸。 </td>
        </tr>
        <tr class="d1">
          <td>int&nbsp;&nbsp; &nbsp;width() const</td>
          <td> 获取当前宽度。 </td>
        </tr>
        <tr>
          <td>int&nbsp;&nbsp; &nbsp;height() const</td>
          <td> 获取当前高度。 </td>
        </tr>
        <tr class="d1">
          <td>QSize&nbsp;&nbsp; &nbsp;minimumSize() const</td>
          <td> 获取最小尺寸。 </td>
        </tr>
        <tr>
          <td>void&nbsp;&nbsp; &nbsp;setMinimumSize(const QSize &amp;)</td>
          <td> 设置最小尺寸。 </td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp; &nbsp;setMinimumSize(int minw, int minh)</td>
          <td> 设置最小尺寸。 </td>
        </tr>
        <tr>
          <td>int&nbsp;&nbsp;&nbsp; minimumWidth() const</td>
          <td style="height: 16px;"> 获取最小宽度。 </td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp;&nbsp; setMinimumWidth(int minw)</td>
          <td> 设置最小宽度。 </td>
        </tr>
        <tr>
          <td>int&nbsp;&nbsp;&nbsp; minimumHeight() const</td>
          <td> 获取最小高度。 </td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp;&nbsp; setMinimumHeight(int minh)</td>
          <td> 设置最小高度。 </td>
        </tr>
        <tr>
          <td>QSize&nbsp;&nbsp;&nbsp; maximumSize() const<br>
          </td>
          <td> 获取最大尺寸。 </td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp; &nbsp;setMaximumSize(const QSize &amp;)</td>
          <td> 设置最大尺寸。 </td>
        </tr>
        <tr>
          <td>void&nbsp;&nbsp;&nbsp; setMaximumSize(int maxw, int maxh)<br>
          </td>
          <td> 设置最大尺寸。 </td>
        </tr>
        <tr class="d1">
          <td style="height: 16px;">int&nbsp;&nbsp; &nbsp;maximumWidth() const</td>
          <td> 获取最大宽度。 </td>
        </tr>
        <tr>
          <td>void&nbsp;&nbsp;&nbsp; setMaximumWidth(int maxw)<br>
          </td>
          <td> 设置最大宽度。 </td>
        </tr>
        <tr class="d1">
          <td>int&nbsp;&nbsp;&nbsp; maximumHeight() const</td>
          <td> 获取最大高度。 </td>
        </tr>
        <tr>
          <td>void&nbsp;&nbsp;&nbsp; setMaximumHeight(int maxh)<br>
          </td>
          <td> 设置最大高度。 </td>
        </tr>
        <tr class="d1">
          <td>QRect&nbsp;&nbsp; &nbsp;rect() const</td>
          <td> 获取窗口客户区矩形，等同于&nbsp; QRect(0, 0, width(), height()) 。 </td>
        </tr>
      </tbody>
    </table>
    <br>
    QSize 包括两个数值：宽度 width() ，高度 height() 。<br>
    QRect 矩形包括四个数值：左上角起点横坐标 x()，左上角起点纵坐标 y() ，矩形宽度 width() ，矩形高度 height() 。<br>
    <br>
    移动窗口或获取窗口位置的函数：<br>
    <br>
    <table class="tabel">
      <tbody>
        <tr class="d1">
          <td style="width: 320px;" align="center"><b>窗口位置函数</b></td>
          <td align="center"><b> 描述</b></td>
        </tr>
        <tr>
          <td>QPoint&nbsp;&nbsp;&nbsp; pos() const</td>
          <td>获取窗口左上角起点位置坐标。</td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp;&nbsp; move(int x, int y)</td>
          <td style="height: 16px;">移动窗口位置，使左上角起点到指定坐标。</td>
        </tr>
        <tr>
          <td>void&nbsp;&nbsp;&nbsp; move(const QPoint &amp;)</td>
          <td>移动窗口位置，使左上角起点到指定坐标。</td>
        </tr>
        <tr class="d1">
          <td>int&nbsp;&nbsp;&nbsp; x() const</td>
          <td>窗口左上角起点位置的横轴坐标。</td>
        </tr>
        <tr>
          <td>int&nbsp;&nbsp;&nbsp; y() const</td>
          <td style="height: 16px;">窗口左上角起点位置的纵轴坐标。</td>
        </tr>
        <tr class="d1">
          <td>const QRect &amp;&nbsp;&nbsp;&nbsp; geometry() const</td>
          <td>窗口客户区几何矩形（不含标题栏边框）。</td>
        </tr>
        <tr>
          <td>void setGeometry(int x, int y, int w, int h)</td>
          <td style="height: 16px;">设置窗口客户区几何矩形，同时设置坐标和尺寸。</td>
        </tr>
        <tr class="d1">
          <td>void&nbsp;&nbsp;&nbsp; setGeometry(const QRect &amp;)</td>
          <td>设置窗口客户区几何矩形。</td>
        </tr>
        <tr>
          <td>QRect&nbsp;&nbsp;&nbsp; frameGeometry() const</td>
          <td style="height: 16px;">窗口包含标题栏边框的整体几何矩形。</td>
        </tr>
        <tr class="d1">
          <td>QSize&nbsp;&nbsp;&nbsp; frameSize() const</td>
          <td>窗口包含标题栏边框的整体尺寸。</td>
        </tr>
      </tbody>
    </table>
    <br>
    <span style="font-weight: bold;">窗口尺寸位置有些函数的计算包含标题和边框，例如：<br>
      x(),&nbsp; y(),&nbsp; frameGeometry(),&nbsp; pos(),&nbsp; move() 。<br>
      另一些函数计算不包括标题栏和边框，就是单指客户区尺寸位置：<br>
      geometry(),&nbsp; width(),&nbsp; height(),&nbsp; rect(), size() 。</span><br>
    <br>
    通过下图直观说明尺寸位置计算：<br>
    <center> <img src="images/ch11/ch11-01-02.png" alt="geo"></center>
    绿色箭头包含标题栏边框，是完整的窗口矩形计算，紫色的箭头是窗口客户区矩形计算。<br>
    一般来说，移动窗口位置时，我们按照窗口整体来计算；<br>
    而缩放窗口尺寸时，按照窗口客户区来计算。<br>
    <br>
    <div class="os2">11.1.2 新建窗口类方式</div>
    <br>
    下面我们通过一个密码管理工具例子，学习新建窗口类的方式，使用多个窗口。<br>
    主窗口显示用户名和密码哈希值列表，通过新建的子窗口来完成修改用户密码的功能。<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 passwordtool，创建路径 D:\QtProjects\ch11，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，<span style="font-weight: bold;">注意修改主窗口类名为 MainWidget，</span>这
    样与后续的子窗口类名作区分，然后点击下一步；<br>
    ④项目管理不修改，点击完成。<br>
    主窗口类名为 MainWidget，对应的界面文件、头文件、源文件名就是
    mainwidget.ui、mainwidget.h、mainwidget.cpp 。<br>
    接下来我们在项目管理器右击项目根 passwordtool ，右键菜单选择“添加新文件...”，进入新建文件对话框：<br>
    <center> <img src="images/ch11/ch11-01-03.png" alt="new1"></center>
    在上面对话框左边一栏选择 “Qt”，然后在中间一栏选择“Qt设计师界面类”，然后点击右下角“Choose...”按钮，进入Qt设计师界面类的选择界面：<br>
    <center> <img src="images/ch11/ch11-01-04.png" alt="new2"></center>
    在中间上半区选择“Widget”，然后点击“下一步”按钮，进入类名编辑界面：<br>
    <center> <img src="images/ch11/ch11-01-05.png" alt="new3"></center>
    我们只需要把类名修改为 FormChangePassword ，下面的头文件、源文件、界面文件名自动修改，不需要手动调整，修改类名之后点击“下一步”，<br>
    <center> <img src="images/ch11/ch11-01-06.png" alt="new4"></center>
    项目管理界面不用动，直接点击“完成”按钮。这样项目就增加了新类的文件：<br>
    formchangepassword.cpp，formchangepassword.h，formchangepassword.ui。<br>
    现在我们有两套界面类，一套是 MainWidget 类主窗口的文件，另一套是 FormChangePassword 类子窗口的文件。<br>
    我们从主窗口开始编辑，我们打开 mainwidget.ui 文件，然后拖入控件：<br>
    <center> <img src="images/ch11/ch11-01-07.png" alt="mainui01" width="800"></center>
    第一行控件分别是标签“用户名”，单行编辑器 lineEditUser，标签“密码”，单行编辑器 lineEditPassword，“添加新用户”按钮
    pushButtonAddUser 。<br>
    第二行左边是列表控件 listWidgetShow ，右边是两个按钮，“修改用户密码”按钮
    pushButtonChangePassword，“删除选定用户”按钮 pushButtonDelUser 。“修改用户密码”按钮就是负责弹出子窗口的功
    能按钮。<br>
    第一行控件按照水平布局；<br>
    第二行先将 pushButtonChangePassword、pushButtonDelUser&nbsp; 两个按钮垂直布局，然后再与
    listWidgetShow 进行水平布局，如下图所示：<br>
    <center> <img src="images/ch11/ch11-01-08.png" alt="mainui02" width="800"></center>
    然后我们选中主窗口 MainWidget，点击上面垂直布局按钮，主窗口的主布局器是垂直布局：<br>
    <center> <img src="images/ch11/ch11-01-09.png" alt="mainui03" width="800"></center>
    布局完成后，我们修改窗口的尺寸为 518* 300。<br>
    然后我们依次右键点击三个按钮，在右键菜单为它们添加 clicked() 信号对应槽函数：<br>
    <center> <img src="images/slots/buttonclicked.png" alt="slot"></center>
    添加好主界面三个按钮的槽函数之后，我们保存并关闭 mainwidget.ui 文件。<br>
    <br>
    接下来我们打开子窗口的界面文件 formchangepassword.ui ，拖入如下控件：<br>
    <center> <img src="images/ch11/ch11-01-10.png" alt="childui01" width="800"></center>
    第一行是标签“用户名”，单行编辑器 lineEditUser；<br>
    第二行是标签“旧密码”，单行编辑器 lineEditOldPassword；<br>
    第三行是标签“新密码”，单行编辑器 lineEditNewPassword；<br>
    第四行是标签“新密码确认”，单行编辑器 lineEditNewPassword2；<br>
    第五行是“修改密码”按钮 pushButtonChange，按钮尺寸拉宽，与上一行两个控件的累计宽度差不多 。<br>
    在右边对象树，选中窗口 FormChangePassword ，然后点击上面的 网格布局器，该窗口使用一个网格布局即可，设置布局后把窗口大小设置为
    280 * 240 ，如下图所示：<br>
    <center> <img src="images/ch11/ch11-01-11.png" alt="childui02" width="800"></center>
    布局设置完成后，我们右击子窗口的 “修改密码”按钮，为该按钮也添加 clicked() 信号对应槽函数 。<br>
    我们右击添加的槽函数自动归属于各自的窗口类，在主窗口右击添加的槽函数自动放到主窗口类，在子窗口右击添加的槽函数自动放到子窗口类。<br>
    按钮的槽函数都添加完成后，我们保存 formchangepassword.ui 文件并关闭该文件。<br>
    <br>
    下面我们先从主窗口代码开始编辑，首先是 mainwidget.h 头文件：<br>
    <div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;">
      </span>MAINWIDGET_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;">MAINWIDGET_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;">&lt;QWidget&gt;</span></pre>
<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;">&lt;QCryptographicHash&gt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//计算密码哈希值</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:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">&lt;QMap&gt;</span><span style=" color:#c0c0c0;">  </span><span
style=" color:#008000;">//保存用户名-密码映射</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:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"formchangepassword.h"</span><span style=" color:#c0c0c0;">  </span><span
style=" color:#008000;">//子窗口类</span></pre>
<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;">&lt;QListWidget&gt;</span></pre>
<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;">&lt;QListWidgetItem&gt;</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;">MainWidget</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;">MainWidget</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;">MainWidget</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;">MainWidget</span><span
style=" color:#000000;">();</span><span style=" color:#c0c0c0;">    </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;">//更新列表控件的显示</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;">UpdateListShow</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;">signals</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;">//发送旧的用户名密码哈希给子窗口，用于修改密码</span></pre>
<pre style=" margin-top:0px; 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;">SendOldUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span>strUser<span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span>baOldHash<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_pushButtonAddUser_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_pushButtonChangePassword_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_pushButtonDelUser_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:#008000;">//手动添加的槽函数，从子窗口接收新的密码哈希值</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:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">RecvNewUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span>strUser<span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span>baNewHash<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;">MainWidget</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;">//保存用户名和密码哈希值</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:#800080;">QMap</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_mapUserAndHash</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;">//子窗口对象指针</span></pre>
<pre style=" margin-top:0px; 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;">FormChangePassword</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">m_pFormChild</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;">//初始化设置</span></pre>
<pre style=" margin-top:0px; 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;">Init</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;">MAINWIDGET_H</span></pre></div>
          我们添加了多个类的头文件包含，QCryptographicHash 类专门用于密码哈希值计算，涵盖常见的密码哈希算法，比如
          MD5、SHA256
          等，密码一般不建议明文直接存储，容易泄密，所以都是将密码通过哈希算法生成哈希值存储。哈希算法是单向计算函数，可以从明文推算哈希值密文，但是反过来难以计算，从而实
          现较为安全的密码存储方式。密码比对时，不需要比对明文密码，只需要验证两个密码的哈希值是否一致。<br>
          我们添加 QMap 模板类声明，用于保存用户名和密码哈希值的键值对；formchangepassword.h
          是子窗口类的头文件；QListWidget 和 QListWidgetItem 是列表控件和列表条目的类。<br>
          在 MainWidget 类声明中，我们手动添加更新列表控件显示的函数 UpdateListShow()。<br>
          手动添加信号 SendOldUserPassword(QString strUser, QByteArray
          baOldHash)，用于给修改密码子窗口发送用户名和旧密码哈希值。<br>
          三个按钮的槽函数是之前界面文件编辑时添加的，后面我们手动添加槽函数 RecvNewUserPassword(QString strUser,
          QByteArray baNewHash)，用于从子窗口接收用户名和修改后的新密码哈希值。<br>
          我们添加 m_mapUserAndHash 模板类对象，保存用户名和密码哈希值的键值对；<br>
          m_pFormChild 是子窗口的指针，用于弹窗修改用户的密码；<br>
          Init() 是用于窗口初始化的代码，在该函数里面新建子窗口。<br>
          <br>
          例子中主窗口和子窗口通过信号和槽函数交互数据，如下图所示：<br>
          <center> <img src="images/ch11/ch11-01-12.png" alt="sig-slot" width="600"></center>
          需要发送数据时，通过 emit 触发信号即可。<br>
          下面我们分段编辑主窗口的源文件 mainwidget.cpp，首先是构造函数和初始化函数内容：<br>
          <div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"mainwidget.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_mainwidget.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;">&lt;QMessageBox&gt;</span></pre>
<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;">&lt;QDebug&gt;</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;">MainWidget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">MainWidget</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;">MainWidget</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;">-&gt;</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;">//初始化设置</span></pre>
<pre style=" margin-top:0px; 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;">Init</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;">MainWidget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">MainWidget</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;">//删除子窗口</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;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_pFormChild</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;">    </span><span style=" color:#800000;">m_pFormChild</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:#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;">//初始化设置</span></pre>
<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;">MainWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">Init</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;">//设置窗口标题栏</span></pre>
<pre style=" margin-top:0px; 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;">setWindowTitle</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;">"用户名密码管理工具"</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;">//密码编辑框隐藏显示</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;">-&gt;</span><span style=" color:#800000;">lineEditPassword</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setEchoMode</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QLineEdit</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Password</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:#800000;">m_pFormChild</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><span style=" color:#c0c0c0;">  </span><span
style=" color:#008000;">//初始化为</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">NULL</span></pre>
<pre style=" margin-top:0px; 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;">//新建子窗口，窗口构造时参数里的</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">parent</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">必须是</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">0</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">或</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">NULL</span></pre>
<pre style=" margin-top:0px; 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_pFormChild</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;">FormChangePassword</span><span
style=" color:#000000;">(</span><span style=" color:#000080;">NULL</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;">//关联信号和槽</span></pre>
<pre style=" margin-top:0px; 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;">//主窗口发送旧的用户名密码哈希给子窗口</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:#000000;">connect</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">SIGNAL</span><span
style=" color:#000000;">(</span>SendOldUserPassword<span style=" color:#000000;">(</span><span
style=" color:#800080;">QString</span><span style=" color:#000000;">,</span><span
style=" color:#800080;">QByteArray</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_pFormChild</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">SLOT</span><span
style=" color:#000000;">(</span>RecvOldUserPassword<span style=" color:#000000;">(</span><span
style=" color:#800080;">QString</span><span style=" color:#000000;">,</span><span
style=" color:#800080;">QByteArray</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;">//子窗口发送新的用户名密码哈希给主窗口</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:#000000;">connect</span><span
style=" color:#000000;">(</span><span style=" color:#800000;">m_pFormChild</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">SIGNAL</span><span
style=" color:#000000;">(</span>SendNewUserPassword<span style=" color:#000000;">(</span><span
style=" color:#800080;">QString</span><span style=" color:#000000;">,</span><span
style=" color:#800080;">QByteArray</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;">this</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">SLOT</span><span
style=" color:#000000;">(</span>RecvNewUserPassword<span style=" color:#000000;">(</span><span
style=" color:#800080;">QString</span><span style=" color:#000000;">,</span><span
style=" color:#800080;">QByteArray</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>
    构造函数末尾添加了 Init() 函数调用，析构函数里面添加了一行删除子窗口对象的代码。<br> Init() 函数首先设置主窗口的标题栏文本为 "用户名密码管理工具" ；<br>将密码编辑框的回显模式修改为 QLineEdit::Password ，就是隐藏输入的字符，用星号或者黑圆点代替；<br>我们先将 m_pFormChild 初始化为 NULL 空指针，然后新建子窗口对象，保存到 m_pFormChild，新建窗口时，参数里的 parent 必须为 0 或 NULL；<br>然后我们将主窗口和子窗口的信号、槽函数进行关联，主窗口将用户名、旧密码传递给子窗口，子窗口修改密码后，再将用户名和新密码回传给主窗口。<br><br>接下来我们编辑更新列表控件显示的函数，当用户名密码列表变化时，调用这个函数更新显示：<br>
    <div class="code"><span style=" color:#008000;">//更新列表控件的显示</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;">MainWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">UpdateListShow</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;">//清除旧列表</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:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">listWidgetShow</span><span
style=" color:#000000;">-&gt;</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;">//根据映射重新显示</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:#808000;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nCount</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mapUserAndHash</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">count</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;">//获取所有key，就是用户名</span></pre>
<pre style=" margin-top:0px; 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;">QList</span><span
style=" color:#000000;">&lt;</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">&gt;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">listKeys</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mapUserAndHash</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">keys</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:#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;">&lt;</span><span style=" color:#000000;">nCount</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:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curKey</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">listKeys</span><span style=" color:#000000;">[</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:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curKey</span><span style=" color:#c0c0c0;"> </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:#008000;">"\t"</span><span style=" color:#000000;">)</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">+</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mapUserAndHash</span><span style=" color:#000000;">[</span><span
style=" color:#000000;">curKey</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;">-&gt;</span><span style=" color:#800000;">listWidgetShow</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">addItem</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTemp</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:#000000;">}</span></pre></div>
    我们先清空列表控件旧的内容，然后获取用户密码键值对的计数，获取所有的键，也就是用户名列表；<br>然后循环处理映射对象中每个键值对，将用户名和密码哈希值通过 "\t" 拼接成一个字符串，添加为列表控件的一行。<br>循环结束之后，就完成了列表控件的更新。<br><br>
    接下来我们编辑“添加新用户”按钮槽函数的代码：<br>
    <div class="code"><span style=" color:#008000;">//添加新用户</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;">MainWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonAddUser_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;">//获取用户名和密码字符串</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;">strNewUser</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;">-&gt;</span><span
style=" color:#800000;">lineEditUser</span><span style=" color:#000000;">-&gt;</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:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPassword</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;">-&gt;</span><span
style=" color:#800000;">lineEditPassword</span><span style=" color:#000000;">-&gt;</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;">strNewUser</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><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strPassword</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:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</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;">"用户名密码检查"</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;">"用户名或密码为空，不能添加。"</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;">//判断是否已存在该用户</span></pre>
<pre style=" margin-top:0px; 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_mapUserAndHash</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">contains</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strNewUser</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:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</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;">"用户名检查"</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;">"已存在该用户名，不能再新增同名。"</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;">//新的用户名，计算哈希</span></pre>
<pre style=" margin-top:0px; 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;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baNewHash</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QCryptographicHash</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">hash</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strPassword</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toUtf8</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;">QCryptographicHash</span><span style=" color:#000000;">::</span><span
style=" color:#800080;">Sha256</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;">//二进制哈希转为Hex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:#000000;">baNewHash</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">baNewHash</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toHex</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;">//新增用户名</span></pre>
<pre style=" margin-top:0px; 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_mapUserAndHash</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;">strNewUser</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baNewHash</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;">UpdateListShow</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>
    该函数先获取用户名和密码的字符串，字符串剔除两端的空白；<br>判断用户名 strNewUser 和密码 strPassword 字符串是否为空，如果有一个为空就弹出信息框提示，然后返回；<br>只有当用户名和密码字符串都不空时，进入后续的处理。<br>
    判断 strNewUser 是否为映射对象已有的键，就是检查用户名是否重复，如果重复就弹出信息框提示，然后返回；<br>当没有重复用户名时，才进行后续的添加操作。<br>我们调用静态函数 QCryptographicHash::hash() 计算密码的 SHA256 哈希值，直接得到的字节数组是二进制格式，不便于显示，因此转为 Hex 十六进制字符串，存到 baNewHash，例如原本一字节 0xa1 的二进制转为两个字符 "a1" 。<br>SHA256 哈希值原本 256 比特（32 字节），转换后就是 64 个十六进制字符。<br>我们将用户名和新的哈希字符串存到映射对象 m_mapUserAndHash，并调用 UpdateListShow() 更新列表控件显示。<br><br>
    接下来我们编辑“删除选定用户”按钮的槽函数：<br>
    <div class="code"><span style=" color:#008000;">//删除选中行的用户</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;">MainWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonDelUser_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;">//列表当前行号</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;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curIndex</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;">-&gt;</span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">currentRow</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;">curIndex</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</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;">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;">//当前行号的条目</span></pre>
<pre style=" margin-top:0px; 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;">QListWidgetItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">curItem</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;">-&gt;</span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">item</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curIndex</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;">curItem</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">isSelected</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;">//处于选中状态，才删除该行</span></pre>
<pre style=" margin-top:0px; 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;">//该条目处于选中状态</span></pre>
<pre style=" margin-top:0px; 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;">curLine</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curItem</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</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;">QStringList</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curKeyValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curLine</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">split</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">'\t'</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;">//删除键值对</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:#800000;">m_mapUserAndHash</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:#000000;">curKeyValue</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></pre>
<pre style=" margin-top:0px; 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;">//卸下条目</span></pre>
<pre style=" margin-top:0px; 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;">-&gt;</span><span style=" color:#800000;">listWidgetShow</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">takeItem</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">curIndex</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;">//删除条目</span></pre>
<pre style=" margin-top:0px; 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:#000000;">curItem</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curItem</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:#000000;">}</span></pre>
<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>
    我们获取列表控件的当前行号，如果行号为 -1 就不处理；<br>行号合法时，我们获取该行的条目存到 curItem 指针；<br>判断该条目是否处于选中状态，只有选中该条目的情况才进行删除操作：<br>获取该行条目的文本，使用 '\t' 切分字符串，切分后形成两个字符串，第 0 段是用户名，第 1 段是密码哈希字符串；<br>我们根据用户名删除映射对象里匹配的键值对，就删除了该用户和哈希值；<br>从列表控件卸下该行条目，并手动删除卸下条目的内存，这样就完成了用户的删除和界面列表控件的更新。<br><br>
    接下来我们编辑“修改用户密码”按钮的槽函数代码：<br>
    <div class="code"><span style=" color:#008000;">//弹出子窗口，进行密码修改</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;">MainWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonChangePassword_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;">//列表当前行号</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;">int</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curIndex</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;">-&gt;</span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">currentRow</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;">curIndex</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&lt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000080;">0</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;">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;">//当前行号的条目</span></pre>
<pre style=" margin-top:0px; 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;">QListWidgetItem</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#000000;">curItem</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;">-&gt;</span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">item</span><span style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curIndex</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;">curItem</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">isSelected</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;">//处于选中状态，才会修改该行密码</span></pre>
<pre style=" margin-top:0px; 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;">//该条目处于选中状态</span></pre>
<pre style=" margin-top:0px; 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;">curLine</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curItem</span><span style=" color:#000000;">-&gt;</span><span
style=" color:#000000;">text</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;">QStringList</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">curKeyValue</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curLine</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">split</span><span style=" color:#000000;">(</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">'\t'</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;">strUser</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">curKeyValue</span><span style=" color:#000000;">[</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:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baOldHash</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_mapUserAndHash</span><span style=" color:#000000;">[</span><span
style=" color:#000000;">strUser</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;">//发送用户名和哈希给子窗口</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;">emit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">SendOldUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">strUser</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baOldHash</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;">//显示修改密码的子窗口</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:#800000;">m_pFormChild</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">show</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;">//如果子窗口被最小化，显示原本尺寸的窗口</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_pFormChild</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">isMinimized</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;">m_pFormChild</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">showNormal</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;">m_pFormChild</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">raise</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>
    该函数开头也是获取列表控件当前行序号 curIndex，并判断如果行号为 -1，直接返回不处理。<br>行号合法时才获取该行的条目 curItem，并判断条目处于选中状态时，才进行修改密码的操作：<br>我们获取该行条目的文本，并按照 '\t' 进行拆分，得到两段字符串，前半截 curKeyValue[0] 是用户名字符串 strUser， 后半截是密码哈希字符串，我们这里从映射对象读取哈希字符串，存到 baOldHash，这样得到的哈希数据类型是 QByteArray 。<br>
    得到用户名和旧密码哈希之后，我们触发信号 SendOldUserPassword(strUser, baOldHash) ，将数据交给子窗口槽函数处理。<br>然后我们弹出子窗口 m_pFormChild 显示，如果子窗口之前被用户操作最小化了，那么使用 m_pFormChild-&gt;showNormal() 显示还原正常尺寸的子窗口；最后调用 m_pFormChild-&gt;raise() ，让子窗口显示到最前面，成为用户操作焦点。后续的密码修改操作由子窗口处理。<br>
    <br>当子窗口的密码修改操作完成后，会发送用户名和新的密码哈希给主窗口，
    我们在主窗口通过 RecvNewUserPassword() 槽函数接收这些数据，主窗口这个槽函数代码如下：<br>
    <div class="code"><span style=" color:#008000;">//手动添加的槽函数，从子窗口接收新的密码哈希值</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;">MainWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">RecvNewUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strUser</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baNewHash</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;">//修改用户的密码哈希值</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:#800000;">m_mapUserAndHash</span><span
style=" color:#000000;">[</span><span style=" color:#000000;">strUser</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;">baNewHash</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;">UpdateListShow</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;">//修改完成，隐藏子窗口</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:#800000;">m_pFormChild</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">hide</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;">//提示修改完成</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:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</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;">"修改密码"</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;">"修改密码成功。"</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>
    我们根据收到的用户名和新密码哈希，修改映射对象的键值对，然后更新列表控件显示；<br>因为修改操作完成了，所以我们调用 m_pFormChild-&gt;hide() 隐藏子窗口；<br>最后弹窗提示，修改密码成功。<br>
    <br>以上就是主窗口的代码，下面我们编辑子窗口的头文件 formchangepassword.h 代码：<br>
    <div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;"> </span>FORMCHANGEPASSWORD_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;">FORMCHANGEPASSWORD_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;">&lt;QWidget&gt;</span></pre>
<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;">&lt;QCryptographicHash&gt;</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">//计算密码哈希值</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:#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;">FormChangePassword</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;">FormChangePassword</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;">FormChangePassword</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;">FormChangePassword</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;">signals</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;">//发送新的密码哈希给主窗口</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;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">SendNewUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span>strUser<span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span>baNewHash<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_pushButtonChange_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:#008000;">//手动添加的槽函数，从主窗口接收旧的用户名和密码哈希</span></pre>
<pre style=" margin-top:0px; 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;">RecvOldUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span>strUser<span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span>baOldHash<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;">FormChangePassword</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;">//初始化设置</span></pre>
<pre style=" margin-top:0px; 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;">Init</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;">//保存用户名和密码哈希值</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:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_strUser</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;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_baOldHash</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;">FORMCHANGEPASSWORD_H</span></pre>
</div>
    子窗口头文件也添加 QCryptographicHash 密码哈希计算类的包含，后面要计算密码哈希值。<br>子窗口类的声明里面，我们手动添加了信号 SendNewUserPassword(QString strUser, QByteArray baNewHash)，
    用于回传用户名新密码哈希值给主窗口；<br>手动添加了槽函数 RecvOldUserPassword(QString strUser, QByteArray baOldHash)，用于从主窗口接收用户名和旧密码哈希值。<br>然后添加了子窗口初始化函数 Init()，以及两个成员变量 m_strUser、m_baOldHash，存储用户名和旧密码哈希值。<br>
    <br>接下来我们分段编辑子窗口的源文件  formchangepassword.cpp 代码，首先是构造函数和初始化部分：<br>
    <div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"formchangepassword.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_formchangepassword.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;">&lt;QMessageBox&gt;</span></pre>
<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;">&lt;QDebug&gt;</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;">FormChangePassword</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">FormChangePassword</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;">FormChangePassword</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;">-&gt;</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</span></pre>
<pre style=" margin-top:0px; 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;">Init</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;">FormChangePassword</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">FormChangePassword</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;">//初始化设置</span></pre>
<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;">FormChangePassword</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">Init</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;">//修改窗口标题栏</span></pre>
<pre style=" margin-top:0px; 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;">setWindowTitle</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;">"修改用户密码"</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;">//设置密码隐藏</span></pre>
<pre style=" margin-top:0px; 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;">-&gt;</span><span style=" color:#800000;">lineEditOldPassword</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setEchoMode</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QLineEdit</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Password</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;">-&gt;</span><span style=" color:#800000;">lineEditNewPassword</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setEchoMode</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QLineEdit</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Password</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;">-&gt;</span><span style=" color:#800000;">lineEditNewPassword2</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setEchoMode</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QLineEdit</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Password</span><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;">//用户名为只读</span></pre>
<pre style=" margin-top:0px; 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;">-&gt;</span><span style=" color:#800000;">lineEditUser</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">-&gt;</span><span style=" color:#800000;">lineEditUser</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setStyleSheet</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">"background-color:</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">rgb(200,200,255);"</span><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;">//工具提示</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;">-&gt;</span><span style=" color:#800000;">lineEditOldPassword</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setToolTip</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;">"旧密码验证成功才能修改为新密码。"</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>
    构造函数末尾添加了初始化函数 Init() 调用。<br>
     Init() 函数首先修改子窗口标题栏文本为 "修改用户密码"，直观说明这个子窗口的功能；<br>然后把三个密码编辑框的回显模式修改为密码模式，就是将输入字符用星号或黑圆点代替显示；<br>接着把用户名的编辑框设置为只读，并设置用户名编辑框的背景为浅蓝色，这个子窗口功能只是改密码，不能修改用户名。<br>通常用户名是唯一的，不能随便修改，所以这里设置用户名为只读的。<br>我们设置旧密码编辑框的工具提示信息，说明只有旧密码输入对了，才能修改新密码，加了一层验证，只有知道原先的密码才能改新密码。这个功能一般是防止非法用户偷偷使用别人电脑修改别人的密码。<br>
    <br>接下来我们编辑从主窗口接收数据的槽函数：<br>
    <div class="code"><span style=" color:#008000;">//手动添加的槽函数，从主窗口接收旧的用户名和密码哈希</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;">FormChangePassword</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">RecvOldUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strUser</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baOldHash</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;">//存到成员变量</span></pre>
<pre style=" margin-top:0px; 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_strUser</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strUser</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_baOldHash</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">baOldHash</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;">//设置用户名</span></pre>
<pre style=" margin-top:0px; 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;">-&gt;</span><span style=" color:#800000;">lineEditUser</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#800000;">m_strUser</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;">//清空密码编辑框</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:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">lineEditOldPassword</span><span
style=" color:#000000;">-&gt;</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:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">lineEditNewPassword</span><span
style=" color:#000000;">-&gt;</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:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">lineEditNewPassword2</span><span
style=" color:#000000;">-&gt;</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:#000000;">}</span></pre></div>
    从主窗口信号收到用户名和旧密码哈希值后，我们保存这些数据到成员变量 strUser 和 baOldHash ；<br>然后通过代码设置用户名编辑框的内容，编辑框的只读属性是指用户不能用鼠标键盘操作修改，程序员可以通过代码修改编辑框内容。<br>设置用户名之后，我们清空三个密码编辑框的内容，让用户输入这三个密码框内容。<br><br>
    子窗口只有一个“修改密码”按钮，我们现在编辑这个按钮的槽函数：<br>
    <div class="code"><span style=" color:#008000;">//修改密码操作</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;">FormChangePassword</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonChange_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;">//先获取三个密码字符串</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;">strOldPassword</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;">-&gt;</span><span
style=" color:#800000;">lineEditOldPassword</span><span style=" color:#000000;">-&gt;</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:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strNewPassword</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;">-&gt;</span><span
style=" color:#800000;">lineEditNewPassword</span><span style=" color:#000000;">-&gt;</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:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strNewPassword2</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;">-&gt;</span><span
style=" color:#800000;">lineEditNewPassword2</span><span style=" color:#000000;">-&gt;</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:#008000;">//判断密码字符串是否为空</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:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strOldPassword</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><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strNewPassword</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">isEmpty</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:#c0c0c0;"> </span><span style=" color:#000000;">strNewPassword2</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:#800080;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</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;">"密码框检查"</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;">"三个密码都不能为空。"</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:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strNewPassword</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strNewPassword2</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;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</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;">"新密码检查"</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;">"两个新密码不一致。"</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;">//根据旧密码计算旧的哈希值</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:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baOldHashCheck</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QCryptographicHash</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">hash</span><span style=" color:#000000;">(</span><span style=" color:#000000;">strOldPassword</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">toUtf8</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;">QCryptographicHash</span><span style=" color:#000000;">::</span><span
style=" color:#800080;">Sha256</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;">//转为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">Hex</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">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:#000000;">baOldHashCheck</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">baOldHashCheck</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toHex</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;">baOldHashCheck</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">!=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_baOldHash</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;">QMessageBox</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">information</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</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;">"旧密码检查"</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;">"输入的旧密码不正确，不能修改密码。"</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;">//旧密码正确了</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:#800080;">QByteArray</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baNewHash</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QCryptographicHash</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">hash</span><span style=" color:#000000;">(</span><span style=" color:#000000;">strNewPassword</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">toUtf8</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;">QCryptographicHash</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">Sha256</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;">//转为Hex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:#000000;">baNewHash</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">baNewHash</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">toHex</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;">//发送信号，后面交给主窗口处理</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;">emit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">SendNewUserPassword</span><span
style=" color:#000000;">(</span><span style=" color:#800000;">m_strUser</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">baNewHash</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>
    该函数先获取三个密码框输入的字符串，剔除字符串两端的空白；<br>判断三个密码字符串是否有空的，如果有空的旧弹窗提示，直接返回；<br>三个密码字符串都是非空，才继续后面操作。<br>然后判断两个新密码字符串是否相等，如果不相等，说明输入有误，弹窗提示并返回；<br>只有两个新密码字符串相等，才进行后续操作。<br>我们根据用户输入的旧密码字符串计算哈希，并转为 Hex 字符串，存到 baOldHashCheck，将这个字符串与成员变量保存的旧密码哈希字符串对比，如果二者不相等，旧密码输入错误，直接弹窗提示并返回；<br>如果二者相等，说明用户输入的旧密码验证是对的，进入后面的修改密码操作：<br>根据新密码计算 SHA256 哈希值，并转为 Hex 字符串，就是新的密码哈希字符串；<br>触发信号SendNewUserPassword()，将用户名和新密码哈希字符串发送给主窗口，<br>主窗口槽函数 RecvNewUserPassword() 会进行后面的操作。<br><br>主窗口和子窗口通过两对信号-槽函数，完成了相互的数据传递。代码讲解到这，我们生成项目，运行这个例子，添加一个用户名 a，密码用简单的 123，
    添加新用户：<br>
    <center> <img src="images/ch11/ch11-01-13.png" alt="run01"></center>
    密码 123 很简单，但是计算的哈希字符串很复杂，避免密码明文的泄露。<br>我们点击选中 a 用户的行，然后点击“修改用户密码”，弹出子窗口：<br>
    <center> <img src="images/ch11/ch11-01-14.png" alt="run02"></center>
    这时我们把三个密码框都输入 1 ，点击“修改密码”按钮，出现提示：<br>
    <center> <img src="images/ch11/ch11-01-15.png" alt="run03"></center>
    旧密码输入错误，不能修改密码。然后我们将旧密码修改为正确的 123 ，再点击“修改密码”按钮：<br>
    <center> <img src="images/ch11/ch11-01-16.png" alt="run04"></center>
    旧密码输入正确，就能修改为新密码了，并且修改密码的子窗口自动隐藏了，回到了主窗口的界面。<br>密码管理工具通常还需要加入复杂密码验证，比如需要字母、数字、标点符号、大小写、密码长度等检查，帮助用户设置更加复杂更安全的密码。本例子只是简单演示，现实中都应该使用安全性高的密码。<br>这个例子的内容介绍到这，下面我们学习将已有的窗口类集成到项目里，作为子窗口弹出显示。<br>
    <br>
    <div class="os2">11.1.3 集成已有窗口类方式</div>
    <br>
    下面的例子，我们通过集成已有窗口类的方式，使用多个窗口。我们对 10.3.2 小节文件属性的例子进行重新设计，使用主窗口显示文件名称、大小、修改时间等内容，通过一个按钮弹出子窗口，用子窗口预览文件内容，子窗口就是 10.3.2 小节文件属性例子中的 TabPreview 类文件，我们复制过来， TabPreview 类文件一个字母都不用修改，就可以集成到新项目里面使用。信号和槽机制就完美实现了多个窗口之间的数据交互，而且是松耦合的，模块独立性很强，在新项目集成原有的类，原有类的代码都不需要做修改。下面我们开始这个例子。<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 fileattrshow，创建路径 D:\QtProjects\ch11，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，<span
style="font-weight: bold;">注意修改主窗口类名为 FileAttrWidget，</span>这样与其他窗口类名作区分，然后点击下一步；<br>④项目管理不修改，点击完成。<br>主窗口类名为 FileAttrWidget，对应的界面文件、头文件、源文件名就是 fileattrwidget.ui、fileattrwidget.h、fileattrwidget.cpp 。<br><br>我们把 10.3.2 小节文件属性的例子里面的三个文件 tabpreview.cpp、tabpreview.h、tabpreview.ui 复制粘贴到本示例 fileattrshow 项目文件夹中。<br>接下来我们在项目管理器右击项目根 fileattrshow，右键菜单选择“添加现有文件...”，
 弹出添加现有文件对话框：<br>
 <center> <img src="images/ch11/ch11-01-17.png" alt="add01"></center>
 我们选中 tabpreview.cpp、tabpreview.h、tabpreview.ui 三个文件，然后点击“打开”按钮，这三个已有类的文件就添加给了本项目。<br>添加文件之后，QtCreator 如果出现左下角三角箭头变为灰色，不能构建项目的情况，就点击三角箭头上面的 Debug 按钮，将 Debug 和 Release 构建来回切换一下即可。<br> 将 TabPreview 类文件添加到项目之后，该类三个文件的内容我们一个字母都不用修改。<br><br>
 下面我们打开主窗口的   fileattrwidget.ui 界面文件，拖入如下控件：<br>
 <center> <img src="images/ch11/ch11-01-18.png" alt="main01" width="800"></center>


 界面第一行是标签“文件全名”，单行编辑器 lineEditFullName，“选择文件”按钮 pushButtonSelectFile；<br>第二行是标签“文件短名”，单行编辑器 lineEditShortName，“预览文件”按钮 pushButtonPreview；<br>第三行是标签“文件大小”，单行编辑器 lineEditFileSize；<br>第四行是标签“创建时间”，单行编辑器 lineEditTimeCreated；<br>第四行是标签“访问时间”，单行编辑器 lineEditTimeRead；<br>第四行是标签“修改时间”，单行编辑器 lineEditTimeModified 。<br>将这些控件拖动排列整齐，然后在右侧对象树一栏选择窗口根 FileAttrWidget，
 点击上面网格布局按钮，将所有控件按照网格布局，如下图所示：<br>
 <center> <img src="images/ch11/ch11-01-19.png" alt="main02" width="800"></center>
 完成布局后，我们依次右键点击两个按钮，为每个按钮添加 clicked() 信号的槽函数：<br>
 <center> <img src="images/slots/buttonclicked.png" alt="slot"></center>
 两个按钮槽函数添加完成后，我们保存并关闭界面文件。<br><br>下面我们编辑主窗口头文件 fileattrwidget.h 内容：<br>
 <div class="code"><span style=" color:#000080;">#ifndef</span><span style=" color:#c0c0c0;"> </span>FILEATTRWIDGET_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;">FILEATTRWIDGET_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;">&lt;QWidget&gt;</span></pre>
<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;">&lt;QFile&gt;</span></pre>
<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;">&lt;QFileInfo&gt;</span></pre>
<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;">&lt;QFileDialog&gt;</span></pre>
<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;">"tabpreview.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:#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;">FileAttrWidget</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;">FileAttrWidget</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;">FileAttrWidget</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;">FileAttrWidget</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;">signals</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;">//文件名变化时触发该信号</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;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileNameChanged</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">const</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800080;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">&amp;</span>fileName<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_pushButtonSelectFile_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_pushButtonPreview_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;">FileAttrWidget</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;">//子窗口指针</span><span
style=" color:#c0c0c0;">    </span></pre>
<pre style=" margin-top:0px; 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;">TabPreview</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">*</span><span style=" color:#800000;">m_pPreviewWnd</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;">//文件全名</span></pre>
<pre style=" margin-top:0px; 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:#800000;">m_strFileName</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;">//文件信息查看对象</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:#800080;">QFileInfo</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_fileInfo</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:#808000;">void</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">Init</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;">FILEATTRWIDGET_H</span></pre>
</div>
    我们添加了文件、文件信息、文件对话框等类的头文件包含，并添加了子窗口类头文件 tabpreview.h 包含。<br>在主窗口类声明里，添加信号 fileNameChanged(const QString &amp;fileName)，用于给子窗口发送文件名，不管是给子控件还是子窗口发数据，信号和槽函数的使用是一模一样的。<br>主窗口类声明里两个槽函数是通过界面文件编辑时为按钮添加的。<br>我们添加了子窗口的指针 m_pPreviewWnd，文件名字符串 m_strFileName，文件信息查看对象 m_fileInfo。<br>最后添加了一个初始化函数，用于新建子窗口、关联信号和槽等功能。<br><br>
 下面我们分段编辑主窗口源文件 fileattrwidget.cpp 内容，首先是构造函数和初始化部分：<br>
 <div class="code"><span style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">"fileattrwidget.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_fileattrwidget.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;">&lt;QMessageBox&gt;</span></pre>
<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;">&lt;QDebug&gt;</span></pre>
<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;">&lt;QDateTime&gt;</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;">FileAttrWidget</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">FileAttrWidget</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;">FileAttrWidget</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;">-&gt;</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;">Init</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;">FileAttrWidget</span><span style=" color:#000000;">::~</span><span
style=" font-style:italic; color:#000000;">FileAttrWidget</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;">//删除子窗口</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;">delete</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_pPreviewWnd</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;">   </span><span style=" color:#800000;">m_pPreviewWnd</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:#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=" 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:#808000;">void</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">FileAttrWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">Init</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;">//单行编辑器都设置为只读</span></pre>
<pre style=" margin-top:0px; 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;">-&gt;</span><span style=" color:#800000;">lineEditFullName</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">-&gt;</span><span style=" color:#800000;">lineEditShortName</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">-&gt;</span><span style=" color:#800000;">lineEditFileSize</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">-&gt;</span><span style=" color:#800000;">lineEditTimeCreated</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">-&gt;</span><span style=" color:#800000;">lineEditTimeRead</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">-&gt;</span><span style=" color:#800000;">lineEditTimeModified</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setReadOnly</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">true</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;">//指针初始化为</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">NULL</span></pre>
<pre style=" margin-top:0px; 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_pPreviewWnd</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;">//新建子窗口</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:#800000;">m_pPreviewWnd</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;">TabPreview</span><span
style=" color:#000000;">(</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;">//设置子窗口标题栏</span></pre>
<pre style=" margin-top:0px; 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_pPreviewWnd</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setWindowTitle</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">tr</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"预览文件"</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;">//关联信号和槽函数，传递文件名给子窗口</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:#000000;">connect</span><span
style=" color:#000000;">(</span><span style=" color:#808000;">this</span><span style=" color:#000000;">,</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">SIGNAL</span><span
style=" color:#000000;">(</span>fileNameChanged<span style=" color:#000000;">(</span><span
style=" color:#800080;">QString</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_pPreviewWnd</span><span
style=" color:#000000;">,</span><span style=" color:#c0c0c0;"> </span><span style=" color:#808000;">SLOT</span><span
style=" color:#000000;">(</span>onFileNameChanged<span style=" color:#000000;">(</span><span
style=" color:#800080;">QString</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>
    我们添加了信息框、调试输出和日期时间类的头文件包含。在构造函数末尾调用初始化函数 Init() 。<br>析构函数里面删除了新建的子窗口对象。<br>Init() 初始化函数中，我们先把 6 个编辑框设置为只读，因为程序不会修改文件的属性。<br>然后我们把 m_pPreviewWnd 初始化为 NULL，然后新建子窗口对象，保存到 pPreviewWnd ；<br>设置子窗口的标题文本为 "预览文件"，直观显示子窗口功能；<br>然后将主窗口的 fileNameChanged(QString) 信号关联到子窗口槽函数 onFileNameChanged(QString)，就可以实现窗口之间信息的传递。<br>
    <br>接下来我们编辑“选择文件”按钮槽函数的代码：<br>
    <div class="code"><span style=" color:#008000;">//选择文件</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;">FileAttrWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonSelectFile_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;">QString</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800080;">QFileDialog</span><span style=" color:#000000;">::</span><span
style=" color:#000000;">getOpenFileName</span><span style=" color:#000000;">(</span><span
style=" color:#808000;">this</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;">"选择文件"</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;">tr</span><span
style=" color:#000000;">(</span><span style=" color:#008000;">""</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;">"All</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">files(*)"</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;">strName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strName</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span><span
style=" color:#c0c0c0;">    </span><span style=" color:#008000;">//剔除空格</span></pre>
<pre style=" margin-top:0px; 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;">strName</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:#808000;">return</span><span
style=" color:#000000;">;</span><span style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//名字为空</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;">//获取了正常文件名</span></pre>
<pre style=" margin-top:0px; 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_strFileName</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#000000;">strName</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_fileInfo</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">setFile</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_strFileName</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;">//文件大小</span></pre>
<pre style=" margin-top:0px; 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;">qint64</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">nFileSize</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_fileInfo</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">size</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;">//设置全名、短名、大小三个编辑框</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:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">lineEditFullName</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_strFileName</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;">-&gt;</span><span style=" color:#800000;">lineEditShortName</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_fileInfo</span><span
style=" color:#000000;">.</span><span style=" color:#000000;">fileName</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;">-&gt;</span><span style=" color:#800000;">lineEditFileSize</span><span
style=" color:#000000;">-&gt;</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;">"%1</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;">字节"</span><span style=" color:#000000;">).</span><span style=" color:#000000;">arg</span><span
style=" color:#000000;">(</span><span style=" color:#000000;">nFileSize</span><span
style=" color:#000000;">)</span><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;">//三个时间字符串</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;">strTimeCreated</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_fileInfo</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">created</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">toString</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"yyyy-MM-dd</span><span style=" color:#c0c0c0;">  </span><span
style=" color:#008000;">HH:mm:ss"</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;">strTimeRead</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_fileInfo</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">lastRead</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">toString</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"yyyy-MM-dd</span><span style=" color:#c0c0c0;">  </span><span
style=" color:#008000;">HH:mm:ss"</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;">strTimeModified</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">=</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#800000;">m_fileInfo</span><span style=" color:#000000;">.</span><span
style=" color:#000000;">lastModified</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">toString</span><span style=" color:#000000;">(</span><span
style=" color:#008000;">"yyyy-MM-dd</span><span style=" color:#c0c0c0;">  </span><span
style=" color:#008000;">HH:mm:ss"</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;">//设置时间编辑框</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:#800000;">ui</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#800000;">lineEditTimeCreated</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTimeCreated</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;">-&gt;</span><span style=" color:#800000;">lineEditTimeRead</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTimeRead</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;">-&gt;</span><span style=" color:#800000;">lineEditTimeModified</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setText</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">strTimeModified</span><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;">//触发文件名称修改的信号</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;">emit</span><span
style=" color:#c0c0c0;"> </span><span style=" color:#000000;">fileNameChanged</span><span
style=" color:#000000;">(</span><span style=" color:#800000;">m_strFileName</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>
    我们使用文件打开对话框获取文件名存到 strName，剔除字符串两端的空格；<br>判断 strName 是否为空，如果为空就返回，不处理；<br>strName 不为空的时候，我们将文件名存到成员变量 m_strFileName；<br>设置文件信息查看对象 m_fileInfo 文件名为 strFileName；获取文件大小存到 nFileSize；<br>设置文件全名、文件短名和文件大小三个编辑框的内容；<br>我们使用 m_fileInfo 对象的三个函数获取文件的创建时间、最后访问时间、最后修改时间，<br>构造时间字符串存到 strTimeCreated、strTimeRead、strTimeModified ；<br>然后设置三个时间显示编辑框的内容，显示各自的时间字符串；<br>最后触发 fileNameChanged(m_strFileName) 信号，将文件名传递给子窗口。<br>
 <br>
    下面我们编辑“预览文件”按钮的槽函数：<br>
    <div class="code"><span style=" color:#008000;">//预览文件</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;">FileAttrWidget</span><span
style=" color:#000000;">::</span><span style=" color:#000000;">on_pushButtonPreview_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:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_strFileName</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:#008000;">//没有文件名，没有预览</span></pre>
<pre style=" margin-top:0px; 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;">//模态窗口弹出示范</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;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800000;">m_pPreviewWnd</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">isVisible</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;">//窗口处于已经显示，需要先隐藏，设置模态属性后重新显示</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:#800000;">m_pPreviewWnd</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">hide</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;">//应用程序级别的模态显示</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;">m_pPreviewWnd</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">setWindowModality</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#800080;">Qt</span><span
style=" color:#000000;">::</span><span style=" color:#800080;">ApplicationModal</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_pPreviewWnd</span><span
style=" color:#000000;">-&gt;</span><span style=" color:#000000;">show</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;">//模态显示会强制占据前台焦点，只有用户关闭模态窗口才会回到主窗口</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:#000000;">}</span></pre></div>
    函数先检查文件名是否为空，如果为空就返回，不用预览。<br>判断 m_pPreviewWnd 子窗口是否已经显示，如果已经显示就先隐藏该窗口；<br>设置子窗口为应用程序级别的模态窗口类型，然后显示子窗口。<br>模态窗口的显示需要子窗口在未显示的时候设置，这样下次显示的时候就是模态窗口。<br>模态窗口显示之后，会强制占据前台焦点，只有用户关闭模态窗口后，才能回到原来的主窗口。<br><br>本示例的代码就编辑完成了，子窗口类的文件是复制过来的，集成到项目里，不用修改。<br>
    我们直接生成项目，运行例子：<br>
    <center> <img src="images/ch11/ch11-01-20.png" alt="run01"></center>
    我们点击“选择文件”按钮，打开了 ui_tabpreview.h 文件，可以看到该文件的大小和时间等信息。<br>
    然后我们点击“预览文件”按钮，弹出模态子窗口：<br>
    <center> <img src="images/ch11/ch11-01-21.png" alt="run02"></center>
    子窗口功能与&nbsp; 10.3.2 小节文件属性例子中的预览功能一样，只是从标签页子控件换成了独立的子窗口。<br>模态子窗口弹出显示时，如果点击主窗口，会发现无法切回主窗口操作，因为前台焦点被模态窗口占据。<br>关闭模态子窗口后，才能回到主窗口操作。<br>本示例内容介绍到这，留两个小练习，请读者自己完成，下一节我们学习对话框。<br><br>
     <div class="practice">
      <table>
        <tbody>
          <tr>
            <td><img src="images/pics/practice.png" alt="tip"></td>
            <td> <b>练习</b> </td>
          </tr>
        </tbody>
      </table>
      ① 给密码管理工具 passwordtool 示例中的密码输入框增加检测功能，要求密码字符串长度至少为 6，并且同时有字母和数字。<br>
      ② 将 passwordtool 示例子窗口改为模态显示，将 fileattrshow 示例子窗口改为非模态显示。</div>
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