89 使用QUdpSocket实现UDP通信

89.1 创建项目

通过QtCreator，在C:\Users\Minwei\Projects\Qt路径下，创建名为Udp的项目。

89.2 添加资源

C:\Users\Minwei\Projects\Qt\Udp\Udp.qrc：

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<RCC>
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    <qresource prefix="/">
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        <file>images/abort.bmp</file>
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        <file>images/bind.bmp</file>
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        <file>images/clear.bmp</file>
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        <file>images/exit.bmp</file>
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    </qresource>
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</RCC>

89.3 设计界面

C:\Users\Minwei\Projects\Qt\Udp\udpwindow.ui：

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<?xml version="1.0" encoding="UTF-8"?>
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<ui version="4.0">
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 <class>UdpWindow</class>
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 <widget class="QMainWindow" name="UdpWindow">
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  <property name="geometry">
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   <rect>
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    <x>0</x>
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    <y>0</y>
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    <width>696</width>
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    <height>557</height>
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   </rect>
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  </property>
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  <property name="windowTitle">
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   <string>UDP</string>
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  </property>
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  <widget class="QWidget" name="m_central">
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   <layout class="QVBoxLayout" name="m_layoutVer">
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    <item>
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     <layout class="QHBoxLayout" name="m_layoutTop">
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      <item>
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       <widget class="QLabel" name="m_labLocalAddr">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Fixed" vsizetype="Preferred">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>本地地址：</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QComboBox" name="m_comboLocalAddr">
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        <item>
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         <property name="text">
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          <string>0.0.0.0</string>
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         </property>
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        </item>
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        <item>
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         <property name="text">
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          <string>127.0.0.1</string>
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         </property>
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        </item>
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       </widget>
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      </item>
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      <item>
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       <widget class="QLabel" name="m_labLocalPort">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Fixed" vsizetype="Preferred">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>本地端口：</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QLineEdit" name="m_editLocalPort">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>8000</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QLabel" name="m_labRemoteAddr">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Fixed" vsizetype="Preferred">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>远程地址：</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QLineEdit" name="m_editRemoteAddr">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>127.0.0.1</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QLabel" name="m_labRemotePort">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Fixed" vsizetype="Preferred">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>远程端口：</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QLineEdit" name="m_editRemotePort">
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        <property name="sizePolicy">
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         <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
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          <horstretch>0</horstretch>
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          <verstretch>0</verstretch>
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         </sizepolicy>
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        </property>
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        <property name="text">
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         <string>8000</string>
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        </property>
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       </widget>
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      </item>
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     </layout>
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    </item>
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    <item>
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     <widget class="QPlainTextEdit" name="m_editOutput">
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      <property name="frameShape">
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       <enum>QFrame::WinPanel</enum>
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      </property>
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      <property name="readOnly">
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       <bool>true</bool>
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      </property>
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     </widget>
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    </item>
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    <item>
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     <layout class="QHBoxLayout" name="m_layoutBottom">
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      <item>
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       <widget class="QLineEdit" name="m_editSend">
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        <property name="text">
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         <string>Hello World</string>
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        </property>
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       </widget>
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      </item>
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      <item>
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       <widget class="QPushButton" name="m_btnSend">
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        <property name="text">
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         <string>发送</string>
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        </property>
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        <property name="default">
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         <bool>true</bool>
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        </property>
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       </widget>
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      </item>
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     </layout>
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    </item>
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   </layout>
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  </widget>
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  <widget class="QStatusBar" name="m_statusBar"/>
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  <widget class="QToolBar" name="m_toolBar">
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   <property name="windowTitle">
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    <string>工具栏</string>
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   </property>
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   <property name="toolButtonStyle">
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    <enum>Qt::ToolButtonTextBesideIcon</enum>
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   </property>
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   <attribute name="toolBarArea">
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    <enum>TopToolBarArea</enum>
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   </attribute>
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   <attribute name="toolBarBreak">
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    <bool>false</bool>
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   </attribute>
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   <addaction name="m_actBind"/>
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   <addaction name="m_actAbort"/>
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   <addaction name="m_actClear"/>
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   <addaction name="separator"/>
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   <addaction name="m_actExit"/>
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  </widget>
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  <action name="m_actBind">
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   <property name="icon">
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    <iconset resource="Udp.qrc">
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     <normaloff>:/images/bind.bmp</normaloff>:/images/bind.bmp</iconset>
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   </property>
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   <property name="text">
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    <string>绑定</string>
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   </property>
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  </action>
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  <action name="m_actAbort">
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   <property name="icon">
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    <iconset resource="Udp.qrc">
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     <normaloff>:/images/abort.bmp</normaloff>:/images/abort.bmp</iconset>
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   </property>
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   <property name="text">
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    <string>解绑</string>
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   </property>
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   <property name="toolTip">
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    <string>解绑</string>
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   </property>
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  </action>
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  <action name="m_actClear">
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   <property name="icon">
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    <iconset resource="Udp.qrc">
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     <normaloff>:/images/clear.bmp</normaloff>:/images/clear.bmp</iconset>
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   </property>
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   <property name="text">
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    <string>清空</string>
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   </property>
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   <property name="toolTip">
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    <string>清空</string>
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   </property>
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  </action>
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  <action name="m_actExit">
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   <property name="icon">
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    <iconset resource="Udp.qrc">
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     <normaloff>:/images/exit.bmp</normaloff>:/images/exit.bmp</iconset>
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   </property>
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   <property name="text">
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    <string>退出</string>
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   </property>
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   <property name="toolTip">
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    <string>退出</string>
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   </property>
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  </action>
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 </widget>
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 <tabstops>
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  <tabstop>m_comboLocalAddr</tabstop>
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  <tabstop>m_editLocalPort</tabstop>
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  <tabstop>m_editRemoteAddr</tabstop>
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  <tabstop>m_editRemotePort</tabstop>
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  <tabstop>m_editOutput</tabstop>
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  <tabstop>m_editSend</tabstop>
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  <tabstop>m_btnSend</tabstop>
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 </tabstops>
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 <resources>
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  <include location="Udp.qrc"/>
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 </resources>
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 <connections>
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  <connection>
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   <sender>m_actExit</sender>
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   <signal>triggered()</signal>
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   <receiver>UdpWindow</receiver>
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   <slot>close()</slot>
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   <hints>
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    <hint type="sourcelabel">
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     <x>-1</x>
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     <y>-1</y>
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    </hint>
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    <hint type="destinationlabel">
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     <x>399</x>
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     <y>299</y>
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    </hint>
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   </hints>
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  </connection>
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 </connections>
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</ui>

89.4 实现功能

C:\Users\Minwei\Projects\Qt\Udp\udpwindow.h：

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#ifndef UDPWINDOW_H
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#define UDPWINDOW_H
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#include <QMainWindow>
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#include <QLabel>
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#include <QUdpSocket>
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QT_BEGIN_NAMESPACE
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namespace Ui { class UdpWindow; }
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QT_END_NAMESPACE
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class UdpWindow : public QMainWindow
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{
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    Q_OBJECT
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public:
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    UdpWindow(QWidget *parent = nullptr);
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    ~UdpWindow();
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private slots:
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    void on_m_actBind_triggered();
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    void on_m_actAbort_triggered();
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    void on_m_actClear_triggered();
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    void on_m_btnSend_clicked();
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    void on_m_socket_readyRead();
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    void on_m_socket_stateChanged(
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        QAbstractSocket::SocketState socketState);
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    void on_m_socket_error(
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        QAbstractSocket::SocketError socketError);
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private:
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    Ui::UdpWindow *ui;
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    QLabel* m_labSocketState;
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    QLabel* m_labSocketError;
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    QUdpSocket* m_socket;
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};
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#endif // UDPWINDOW_H

C:\Users\Minwei\Projects\Qt\Udp\udpwindow.cpp：

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#include <QHostInfo>
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#include <QMetaEnum>
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#include "udpwindow.h"
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#include "ui_udpwindow.h"
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UdpWindow::UdpWindow(QWidget *parent)
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    : QMainWindow(parent)
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    , ui(new Ui::UdpWindow)
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    , m_labSocketState(new QLabel("套接字状态："))
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    , m_labSocketError(new QLabel(" 套接字错误："))
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    , m_socket(new QUdpSocket(this))
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{
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    ui->setupUi(this);
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    for (QHostAddress address : QHostInfo::fromName(
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        QHostInfo::localHostName()).addresses())
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        if(address.protocol() == QAbstractSocket::IPv4Protocol)
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            ui->m_comboLocalAddr->addItem(address.toString());
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    m_labSocketState->setMinimumWidth(298);
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    ui->m_statusBar->addWidget(m_labSocketState);
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    m_labSocketError->setMinimumWidth(298);
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    ui->m_statusBar->addWidget(m_labSocketError);
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    connect(m_socket, SIGNAL(readyRead()),
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        this, SLOT(on_m_socket_readyRead()));
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    connect(m_socket, SIGNAL(stateChanged(QAbstractSocket::SocketState)),
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        this, SLOT(on_m_socket_stateChanged(QAbstractSocket::SocketState)));
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    connect(m_socket, SIGNAL(error(QAbstractSocket::SocketError)),
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        this, SLOT(on_m_socket_error(QAbstractSocket::SocketError)));
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}
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UdpWindow::~UdpWindow()
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{
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    delete ui;
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}
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void UdpWindow::on_m_actBind_triggered()
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{
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    QHostAddress address(ui->m_comboLocalAddr->currentText());
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    quint16 port = ui->m_editLocalPort->text().toUShort();
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    if (m_socket->bind(address, port))
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        ui->m_editOutput->appendPlainText(QString("绑定%1:%2成功").
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            arg(address.toString()).arg(port));
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    else
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        ui->m_editOutput->appendPlainText(QString("绑定%1:%2失败").
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            arg(address.toString()).arg(port));
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}
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void UdpWindow::on_m_actAbort_triggered()
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{
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    m_socket->abort();
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    ui->m_editOutput->appendPlainText("解除绑定");
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}
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void UdpWindow::on_m_actClear_triggered()
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{
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    ui->m_editOutput->clear();
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}
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void UdpWindow::on_m_btnSend_clicked()
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{
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    QByteArray datagram(ui->m_editSend->text().toUtf8());
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    QHostAddress address(ui->m_editRemoteAddr->text());
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    quint16 port = ui->m_editRemotePort->text().toUShort();
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    qint64 nbytes = m_socket->writeDatagram(datagram, address, port);
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    if (nbytes == -1)
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        ui->m_editOutput->appendPlainText("发送失败");
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    else
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        ui->m_editOutput->appendPlainText(QString("向%1:%2发送%3字节：%4").
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            arg(address.toString()).arg(port).
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            arg(nbytes).arg(QString(datagram)));
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}
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void UdpWindow::on_m_socket_readyRead()
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{
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    while (m_socket->hasPendingDatagrams())
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    {
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        QByteArray datagram(m_socket->pendingDatagramSize(), 0);
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        QHostAddress address;
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        quint16 port;
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        qint64 nbytes = m_socket->readDatagram(
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            datagram.data(), datagram.size(), &address, &port);
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        if (nbytes == -1)
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            ui->m_editOutput->appendPlainText("接收失败");
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        else
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            ui->m_editOutput->appendPlainText(QString("从%1:%2接收%3字节：%4").
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                arg(QHostAddress(address.toIPv4Address()).toString()).
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                arg(port).arg(nbytes).arg(QString(datagram)));
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    }
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}
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void UdpWindow::on_m_socket_stateChanged(
102
    QAbstractSocket::SocketState socketState)
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{
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    m_labSocketState->setText(QString("套接字状态：%1").arg(
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        QMetaEnum::fromType<QAbstractSocket::SocketState>().
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        valueToKey(socketState)));
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}
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void UdpWindow::on_m_socket_error(
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    QAbstractSocket::SocketError socketError)
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{
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    m_labSocketError->setText(QString(" 套接字错误：%1").arg(
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        QMetaEnum::fromType<QAbstractSocket::SocketError>().
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        valueToKey(socketError)));
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}

89.5 测试验证

运行效果如图所示：