背景:
我需要解决一个bug,需要我从xml中读取数据到QDomDocument,然后获取到我想要的目标信息,然后修改该信息。
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Qt QDomComment读写Xml文件(含示例源码)_qt qdomdocument 操做xml-CSDN博客
QDomDocument类可以方便地读取和操作XML文件。优点:易于使用XML文档,缺点是相对较慢。
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示例Xml文档
cpp
<class>
<student sex="男" age="18">
<id>01</id>
<name>张三</name>
</student>
<student sex="女" age="28">
<id>02</id>
<name>李四</name>
</student>
</class>
标签
标签内包含了要传递的信息
它必须成对出现,有开始标签就需要有结束标签。
Xml文件必须包含根元素,它是所有其它元素的父元素
XML文档由元素构成,每个元素包含开始标签,结束标签和元素内容。例如:<id>02</id>
读取Xml文件的信息
cpp
//XML文件路径
QString path = QCoreApplication::applicationDirPath()+"/xxx.xml";
qDebug()<<path;
//打开XML文件
QFile file(path);
if(!file.open(QIODevice::ReadOnly))
{
qDebug()<<"File open faild!";
return-1;
}
//创建QDomDocument对象,用于解析XML
QDomDocument doc;
//通过QFile对象设置QDomDocument的内容
if(!doc.setContent(&file))
{
file.close();
return -1;
}
//关闭文件
file.close();
//解析XML
//获取XML根结点
QDomElement root = doc.documentElement();
//遍历每个student结点
//通过标签名获取结点列表
QDomNodeList studentList = root.elementsByTagName("student");
int listSize = studentList.size();
for(int i = 0; i < listSize; ++i)
{
//通过索引获取QDomElement对象
QDomElement student = studentList.at(i).toElement();
//获取sex属性值
QString sex = student.attribute("sex");
//获取age属性值
QString age = student.attribute("age");
/*
*函数原型为
*QDomElement firstChildElement(const QString &tagName = QString()) const;
*解析:参数tagName是可选的,表示要查询的子元素结点的标签名。如果指定了tagName,则返回
*第一个匹配标签的子元素结点;如果没有指定tagName,则返回第一个子元素结点。
**/
QString studentID = student.firstChildElement("id").text(); //获取id元素节点的文本内容
QString studentName = student.firstChildElement("name").text(); //获取name元素节点的文本内容
qDebug()<<"student:";
qDebug()<<"sex:"<<sex;
qDebug()<<"age:"<<age;
qDebug()<<"studentID:"<<studentID;
qDebug()<<"studentName:"<<studentName;
}
这里我继续使用Qt的.ui文件作为示例(它是以Xml文件的形式进行存储的)
cpp
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>731</width>
<height>460</height>
</rect>
</property>
<property name="windowTitle">
<string>Graphics View绘图</string>
</property>
<widget class="QWidget" name="centralWidget">
<widget class="QWGraphicsView" name="View">
<property name="geometry">
<rect>
<x>10</x>
<y>10</y>
<width>600</width>
<height>400</height>
</rect>
</property>
<property name="renderHints">
<set>QPainter::Antialiasing|QPainter::TextAntialiasing</set>
</property>
<property name="dragMode">
<enum>QGraphicsView::RubberBandDrag</enum>
</property>
</widget>
</widget>
<widget class="QMenuBar" name="menuBar">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>731</width>
<height>30</height>
</rect>
</property>
</widget>
<widget class="QToolBar" name="mainToolBar">
<property name="iconSize">
<size>
<width>16</width>
<height>16</height>
</size>
</property>
<property name="toolButtonStyle">
<enum>Qt::ToolButtonTextUnderIcon</enum>
</property>
<attribute name="toolBarArea">
<enum>TopToolBarArea</enum>
</attribute>
<attribute name="toolBarBreak">
<bool>false</bool>
</attribute>
<addaction name="actZoomIn"/>
<addaction name="actZoomOut"/>
<addaction name="actRestore"/>
<addaction name="separator"/>
<addaction name="actRotateLeft"/>
<addaction name="actRotateRight"/>
<addaction name="actEdit_Front"/>
<addaction name="actEdit_Back"/>
<addaction name="actGroup"/>
<addaction name="actGroupBreak"/>
<addaction name="separator"/>
<addaction name="actEdit_Delete"/>
<addaction name="separator"/>
<addaction name="actQuit"/>
</widget>
<widget class="QStatusBar" name="statusBar"/>
<widget class="QToolBar" name="toolBar">
<property name="windowTitle">
<string>toolBar</string>
</property>
<property name="allowedAreas">
<set>Qt::LeftToolBarArea</set>
</property>
<property name="iconSize">
<size>
<width>16</width>
<height>16</height>
</size>
</property>
<property name="toolButtonStyle">
<enum>Qt::ToolButtonTextUnderIcon</enum>
</property>
<attribute name="toolBarArea">
<enum>LeftToolBarArea</enum>
</attribute>
<attribute name="toolBarBreak">
<bool>false</bool>
</attribute>
<addaction name="actItem_Rect"/>
<addaction name="actItem_Ellipse"/>
<addaction name="actItem_Circle"/>
<addaction name="actItem_Triangle"/>
<addaction name="actItem_Polygon"/>
<addaction name="actItem_Line"/>
<addaction name="actItem_Text"/>
</widget>
<action name="actItem_Rect">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/RECTANGL.BMP</normaloff>:/images/images/RECTANGL.BMP</iconset>
</property>
<property name="text">
<string>矩形</string>
</property>
<property name="toolTip">
<string>添加矩形</string>
</property>
</action>
<action name="actItem_Ellipse">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/ELLIPSE.BMP</normaloff>:/images/images/ELLIPSE.BMP</iconset>
</property>
<property name="text">
<string>椭圆</string>
</property>
<property name="toolTip">
<string>添加椭圆型</string>
</property>
</action>
<action name="actItem_Line">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/LINE.BMP</normaloff>:/images/images/LINE.BMP</iconset>
</property>
<property name="text">
<string>直线</string>
</property>
<property name="toolTip">
<string>添加直线</string>
</property>
</action>
<action name="actEdit_Delete">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/108.bmp</normaloff>:/images/images/108.bmp</iconset>
</property>
<property name="text">
<string>删除</string>
</property>
<property name="toolTip">
<string>删除选中的图元</string>
</property>
</action>
<action name="actQuit">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/132.bmp</normaloff>:/images/images/132.bmp</iconset>
</property>
<property name="text">
<string>退出</string>
</property>
<property name="toolTip">
<string>退出本系统</string>
</property>
</action>
<action name="actItem_Text">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/800.bmp</normaloff>:/images/images/800.bmp</iconset>
</property>
<property name="text">
<string>文字</string>
</property>
<property name="toolTip">
<string>添加文字</string>
</property>
</action>
<action name="actEdit_Front">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/528.bmp</normaloff>:/images/images/528.bmp</iconset>
</property>
<property name="text">
<string>前置</string>
</property>
<property name="toolTip">
<string>居于最前面</string>
</property>
</action>
<action name="actEdit_Back">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/526.bmp</normaloff>:/images/images/526.bmp</iconset>
</property>
<property name="text">
<string>后置</string>
</property>
<property name="toolTip">
<string>居于最后面</string>
</property>
</action>
<action name="actItem_Polygon">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/FREEFORM.BMP</normaloff>:/images/images/FREEFORM.BMP</iconset>
</property>
<property name="text">
<string>梯形</string>
</property>
<property name="toolTip">
<string>添加梯形</string>
</property>
</action>
<action name="actZoomIn">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/zoomin.png</normaloff>:/images/images/zoomin.png</iconset>
</property>
<property name="text">
<string>放大</string>
</property>
<property name="toolTip">
<string>放大</string>
</property>
</action>
<action name="actZoomOut">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/zoomout.png</normaloff>:/images/images/zoomout.png</iconset>
</property>
<property name="text">
<string>缩小</string>
</property>
<property name="toolTip">
<string>缩小</string>
</property>
</action>
<action name="actRotateLeft">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/rotateleft.png</normaloff>:/images/images/rotateleft.png</iconset>
</property>
<property name="text">
<string>左旋转</string>
</property>
<property name="toolTip">
<string>左旋转</string>
</property>
</action>
<action name="actRotateRight">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/rotateright.png</normaloff>:/images/images/rotateright.png</iconset>
</property>
<property name="text">
<string>右旋转</string>
</property>
<property name="toolTip">
<string>右旋转</string>
</property>
</action>
<action name="actRestore">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/420.bmp</normaloff>:/images/images/420.bmp</iconset>
</property>
<property name="text">
<string>恢复</string>
</property>
<property name="toolTip">
<string>恢复大小</string>
</property>
</action>
<action name="actGroup">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/UNGROUP.BMP</normaloff>:/images/images/UNGROUP.BMP</iconset>
</property>
<property name="text">
<string>组合</string>
</property>
<property name="toolTip">
<string>组合</string>
</property>
</action>
<action name="actGroupBreak">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/128.bmp</normaloff>:/images/images/128.bmp</iconset>
</property>
<property name="text">
<string>打散</string>
</property>
<property name="toolTip">
<string>取消组合</string>
</property>
</action>
<action name="actItem_Circle">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/08.JPG</normaloff>:/images/images/08.JPG</iconset>
</property>
<property name="text">
<string>圆形</string>
</property>
<property name="toolTip">
<string>圆形</string>
</property>
</action>
<action name="actItem_Triangle">
<property name="icon">
<iconset resource="res.qrc">
<normaloff>:/images/images/Icon1242.ico</normaloff>:/images/images/Icon1242.ico</iconset>
</property>
<property name="text">
<string>三角形</string>
</property>
<property name="toolTip">
<string>三角形</string>
</property>
</action>
</widget>
<layoutdefault spacing="6" margin="11"/>
<customwidgets>
<customwidget>
<class>QWGraphicsView</class>
<extends>QGraphicsView</extends>
<header location="global">qwgraphicsview.h</header>
</customwidget>
</customwidgets>
<resources>
<include location="res.qrc"/>
</resources>
<connections>
<connection>
<sender>actQuit</sender>
<signal>triggered()</signal>
<receiver>MainWindow</receiver>
<slot>close()</slot>
<hints>
<hint type="sourcelabel">
<x>-1</x>
<y>-1</y>
</hint>
<hint type="destinationlabel">
<x>302</x>
<y>153</y>
</hint>
</hints>
</connection>
</connections>
</ui>
还是有难度的。
最外层是标签ui
内部是
class
widget
layoutdefault
customwidgets
resources
connections
widget内包含
property
widget
action
我读取一下:
cpp
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>731</width>
<height>460</height>
</rect>
</property>
<property name="windowTitle">
<string>Graphics View绘图</string>
</property>
这一段信息吧
读取.ui文件的代码
cpp
//解析XML
QDomNode firstNode = doc.firstChild();
qDebug()<<"版本和编码信息:"<<firstNode.nodeName()<<firstNode.nodeValue(); // "xml" "version='1.0' encoding='UTF-8'"
qDebug()<<"是否是Xml说明:"<<firstNode.isProcessingInstruction();
QDomElement ui = doc.documentElement();
qDebug()<<"root tag:"<<ui.tagName();
qDebug()<<"root nodeType:"<<ui.nodeType(); //QDomNode::ElementNode 1
qDebug()<<"root hasChildNodes:"<<ui.hasChildNodes(); //true
qDebug()<<"root childNodes count:"<<ui.childNodes().count(); //6
qDebug()<<"root hasAttributes:"<<ui.hasAttributes(); //true
qDebug()<<"root hasAttribute version:"<<ui.hasAttribute("version"); //true
QDomElement xWidget = ui.firstChildElement("widget");
qDebug()<<"widget hasAttribute name:"<<xWidget.hasAttribute("name"); //true
qDebug()<<"widget hasAttribute class:"<<xWidget.hasAttribute("class"); //true
QDomElement xProperty = xWidget.firstChildElement("property");
while(!xProperty.isNull())
{
qDebug()<<xProperty.attribute("name");
xProperty = xProperty.nextSiblingElement("property");
}