Qt 解析XML文件 QXmlStreamReader

如何使用QXmlStreamReader来解析格式良好的XML，Qt的文档中指出，它是一种更快、更方便的Qt自己的SAX解析器（QXmlSimpleReader）的替代，它也较快，在某种情况下，比DOM（QDomDocument）更方便。

   解析方法：
void ParseXML::parseXML(QString file_name)
{
    if(file_name.isEmpty())  
       return;  
  
    QFile *file = new QFile(file_name);  
    if(!file->open(QFile::ReadOnly | QFile::Text)) {  
        QMessageBox::information(NULL, QString("title"), QString("open error!"));
        return;  
    }  

    //QXmlStreamReader操作任何QIODevice.
    QXmlStreamReader xml(file);
    QList> persons;

    //解析XML，直到结束
    while(!xml.atEnd() && !xml.hasError())
    {
       //读取下一个element.
       QXmlStreamReader::TokenType token = xml.readNext();

       //如果获取的仅为StartDocument,则进行下一个
       if(token == QXmlStreamReader::StartDocument) {
          continue;
       }

       //如果获取了StartElement,则尝试读取
       if(token == QXmlStreamReader::StartElement){
            //如果为persons，直接进入下一个
            if(xml.name() == "persons"){
                continue;
            }
            
            //如果为person，则对其进行解析
            if(xml.name() == "person"){
                persons.append(this->parsePerson(xml));
            }
        }
    }
  
    if(xml.hasError()){
        QMessageBox::information(NULL, QString("parseXML"), xml.errorString());
    }
    
    //从reader中删除所有设备、数据，并将其重置为初始状态
    xml.clear();
}
 
QMap ParseXML::parsePerson(QXmlStreamReader& xml)
{
    QMap person;

    //检查是否获取person
    if(xml.tokenType() != QXmlStreamReader::StartElement && xml.name() == "person"){
       return person;
    }

    //获取person属性
    QXmlStreamAttributes attributes = xml.attributes();
    if(attributes.hasAttribute("id")) {
       person["id"] = attributes.value("id").toString();
    }
    
    //操作下一个
    xml.readNext();

    while(!(xml.tokenType() == QXmlStreamReader::EndElement && xml.name() == "person")) 
    {
       if(xml.tokenType() == QXmlStreamReader::StartElement){
          if(xml.name() == "name"){
             this->addElementDataToMap(xml, person);
          }
          
          if(xml.name() == "age") {
             this->addElementDataToMap(xml, person);
          }
         
          if(xml.name() == "email") {
             this->addElementDataToMap(xml, person);
          }
         
          if(xml.name() == "website") {
             this->addElementDataToMap(xml, person);
          }
       }
     
       xml.readNext();
    }

    QString id = person["id"];
    QString name = person["name"];
    QString age =  person["age"];
    QString email = person["email"];
    QString website = person["website"];

    return person;
}
 
void ParseXML::addElementDataToMap(QXmlStreamReader& xml, QMap& map) const
{
    if(xml.tokenType() != QXmlStreamReader::StartElement) {
       return;
    }

    QString elementName = xml.name().toString();
    xml.readNext();
    
    if(xml.tokenType() != QXmlStreamReader::Characters) {
       return;
    }
    
    map.insert(elementName, xml.text().toString());
}