QXmlStreamReader解析XML文件

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。

    XML文件：

    

    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());

}

2、简单解析某一元素

1. QFile probeFile ("1.xml");  
2. if( probeFile.open(QIODevice::ReadOnly | QIODevice::Text) )   
3. {  
4.     QXmlStreamReader xmlReader(&probeFile);  
5.     xmlReader.readNext();  
6.     while(!xmlReader.atEnd())  
7.     {  
8.         if (xmlReader.isStartElement())  
9.         {  
10.             if (xmlReader.name() == "description")  
11.             {  
12.                 QString temp = xmlReader.readElementText();  
13.                 qDebug() << temp;  
14.             }  
15.   
16.             if (xmlReader.name() == "computation_date")  
17.             {  
18.                 QString temp = xmlReader.readElementText();  
19.                 qDebug() << temp;  
20.             }  
21.   
22.             if (xmlReader.name() == "transformation")  
23.             {  
24.                 QString temp = xmlReader.readElementText();  
25.                 qDebug() << temp;  
26.             }  
27.         }  
28.           
29.         xmlReader.readNext();  
30.   
31.     }  
32. }