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Sample code sharing for Qt parsing XML

黄舟

Release： 2017-04-13 10:30:24

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How to use QXmlStreamReader to parse well-formed XML, Qt's documentation states that it is a faster and more convenient alternative to Qt's own SAX parser (QXmlSimpleReader), it is also faster, in some cases It is more convenient than DOM (QDomDocument).

XML file:

Sample code sharing for Qt parsing XML

Parsing method:

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());
}

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