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<!DOCTYPE html>
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="content-type">
<title>ch11-01</title>
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<body>
<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() //槽函数，显示窗口<br>
void QWidget::hide() //槽函数，隐藏窗口<br>
bool isVisible() const //是否处于显示状态<br>
virtual void setVisible(bool visible) //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()
//槽函数，将本窗口置于顶层显示<br>
void QWidget::lower() //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() 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()
//激活本窗口，注意本窗口必须处于显示状态才有用<br>
bool isActiveWindow() const
//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() //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() //槽函数，正常尺寸显示<br>
void QWidget::showFullScreen() //槽函数，全屏显示，标题栏隐藏，将窗口主体铺满屏幕</div>
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 windowModality()
const //获取模态状态<br>
void setWindowModality(Qt::WindowModality
windowModality) //设置模态状态<br>
bool isModal() const //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">
pModWnd->setWindowModality(Qt::ApplicationModal); //模态窗口，会阻塞其他窗口<br>
pModWnd->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"> pNormalWnd->show();
//普通窗口显示，多个窗口都能操作，不会阻塞其他窗口<br>
pNormalWnd->raise(); //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 windowTitle()
const //获取标题栏文本<br>
void setWindowTitle(const QString &) //设置标题栏文本<br>
QIcon windowIcon() const
//获取标题栏图标<br>
void setWindowIcon(const QIcon & icon)
//设置标题栏图标<br>
QString windowIconText() const //获取图标的文本<br>
void setWindowIconText(const QString &) //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 size() const</td>
<td> 获取窗口客户区尺寸。 </td>
</tr>
<tr class="d1">
<td>void resize(int w, int h)</td>
<td> 根据宽度高度设置窗口尺寸。 </td>
</tr>
<tr>
<td>void resize(const QSize &)</td>
<td> 设置窗口尺寸。 </td>
</tr>
<tr class="d1">
<td>int width() const</td>
<td> 获取当前宽度。 </td>
</tr>
<tr>
<td>int height() const</td>
<td> 获取当前高度。 </td>
</tr>
<tr class="d1">
<td>QSize minimumSize() const</td>
<td> 获取最小尺寸。 </td>
</tr>
<tr>
<td>void setMinimumSize(const QSize &)</td>
<td> 设置最小尺寸。 </td>
</tr>
<tr class="d1">
<td>void setMinimumSize(int minw, int minh)</td>
<td> 设置最小尺寸。 </td>
</tr>
<tr>
<td>int minimumWidth() const</td>
<td style="height: 16px;"> 获取最小宽度。 </td>
</tr>
<tr class="d1">
<td>void setMinimumWidth(int minw)</td>
<td> 设置最小宽度。 </td>
</tr>
<tr>
<td>int minimumHeight() const</td>
<td> 获取最小高度。 </td>
</tr>
<tr class="d1">
<td>void setMinimumHeight(int minh)</td>
<td> 设置最小高度。 </td>
</tr>
<tr>
<td>QSize maximumSize() const<br>
</td>
<td> 获取最大尺寸。 </td>
</tr>
<tr class="d1">
<td>void setMaximumSize(const QSize &)</td>
<td> 设置最大尺寸。 </td>
</tr>
<tr>
<td>void setMaximumSize(int maxw, int maxh)<br>
</td>
<td> 设置最大尺寸。 </td>
</tr>
<tr class="d1">
<td style="height: 16px;">int maximumWidth() const</td>
<td> 获取最大宽度。 </td>
</tr>
<tr>
<td>void setMaximumWidth(int maxw)<br>
</td>
<td> 设置最大宽度。 </td>
</tr>
<tr class="d1">
<td>int maximumHeight() const</td>
<td> 获取最大高度。 </td>
</tr>
<tr>
<td>void setMaximumHeight(int maxh)<br>
</td>
<td> 设置最大高度。 </td>
</tr>
<tr class="d1">
<td>QRect rect() const</td>
<td> 获取窗口客户区矩形，等同于 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 pos() const</td>
<td>获取窗口左上角起点位置坐标。</td>
</tr>
<tr class="d1">
<td>void 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 move(const QPoint &)</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 x() const</td>
<td>窗口左上角起点位置的横轴坐标。</td>
</tr>
<tr>
<td>int 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 & 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 setGeometry(const QRect &)</td>
<td>设置窗口客户区几何矩形。</td>
</tr>
<tr>
<td>QRect 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 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(), y(), frameGeometry(), pos(), 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(), width(), height(), 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 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;"><QWidget></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QCryptographicHash></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;"><QMap></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;"><QListWidget></span></pre>
<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;"><QListWidgetItem></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;"><</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;">></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;"><QMessageBox></span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#000080;">#include</span><span style=" color:#c0c0c0;"> </span><span
style=" color:#008000;"><QDebug></span></pre>
<pre style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><br></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#800080;">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;">-></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;">-></span><span style=" color:#800000;">lineEditPassword</span><span
style=" color:#000000;">-></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;">-></span><span style=" color:#800000;">listWidgetShow</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">clear</span><span
style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#008000;">//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;"><</span><span style=" color:#800080;">QString</span><span
style=" color:#000000;">></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;"><</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;">-></span><span style=" color:#800000;">listWidgetShow</span><span
style=" color:#000000;">-></span><span style=" color:#000000;">addItem</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">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;">-></span><span
style=" color:#800000;">lineEditUser</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#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;">-></span><span
style=" color:#800000;">lineEditPassword</span><span style=" color:#000000;">-></span><span
style=" color:#000000;">text</span><span style=" color:#000000;">().</span><span
style=" color:#000000;">trimmed</span><span style=" color:#000000;">();</span></pre>
<pre style=" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;"><span
style=" color:#c0c0c0;"> </span><span style=" color:#808000;">if</span><span
style=" color:#000000;">(</span><span style=" color:#c0c0c0;"> </span><span style=" color:#000000;">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;">-></span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-></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;"><</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;">-></span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-></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;">-></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;">-></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;">-></span><span style=" color:#800000;">listWidgetShow</span><span
style=" color:#000000;">-></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;">-></span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-></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;"><</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;">-></span><span
style=" color:#800000;">listWidgetShow</span><span style=" color:#000000;">-></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;">-></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;">-></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