QDomDocument的使用

QDomDocument是QT所封装的类，用来操作XML文件。而xml在项目中的角色常常是用来存储一些配置数据，因此在大部分的项目中会用到两个功能：写XML文件和读取XML文件。具体情况见代码：

#include <QtCore/QCoreApplication>
#include <QDomDocument>
#include <QMap>
#include <QTextStream>
#include <QFile>
#include <iostream>
class CXMLTestData
{
public:
       CXMLTestData();
       CXMLTestData(int num);
       ~CXMLTestData();
       void OutTheData();
       bool          m_bXMLTestData;
       int         m_iTestNum;
       double      m_dChooseNum;
       QString              m_qsXMLDescripe;
       QMap<double , QString>   m_mapXMLData;
       
       bool          m_bFirstChild;
       double      m_dFirstChildChoose;
       QString     m_qsTextNode;
};
CXMLTestData::CXMLTestData()
{
       m_bXMLTestData       = true;
       m_iTestNum = 2226;
       m_dChooseNum = 7920;
       m_qsXMLDescripe = "XML Write Or Read Test!";
       m_mapXMLData[0] = "This is first data.";
       m_mapXMLData[1] = "This is second data.";
       m_mapXMLData[2] = "This is third data";
       m_bFirstChild = true;
       m_dFirstChildChoose = 9898;
       m_qsTextNode = "This is TestNode!";
}
CXMLTestData::CXMLTestData(int num)
{
       m_bXMLTestData = false;
       m_iTestNum = 0;
       m_dChooseNum = 0;
       m_bFirstChild = true;
       m_dFirstChildChoose = 0;
}
CXMLTestData::~CXMLTestData()
{
       
}
void CXMLTestData::OutTheData()
{
       std::cout<< "bXML_TestData = " << m_bXMLTestData << "\n"
              << "iTest_Num = " << m_iTestNum << "\n"
              << "dChoose_Num = " << m_dChooseNum << "\n"
              << "qsXML_Descripe = " << m_qsXMLDescripe.toStdString() << "\n"
              << "mapXMLData_index_0 = " << m_mapXMLData[0].toStdString() << "\n"
              << "mapXMLData_index_1 = " << m_mapXMLData[1].toStdString()