代码出自Qt creator 快速入门，代码如下

从xml中读取数据

main.cpp

#include <QtCore/QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QXmlStreamWriter>
#include <QDebug>

int main(int argc,char *argv[])
{
    QCoreApplication a(argc,argv);

    QFile file("../myXmlStream/my.xml");
    if (!file.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug()<<"Error: cannot open file";
        return 1;
    }

    QXmlStreamReader reader;

    // 设置文件，这时会将流设置为初始状态
    reader.setDevice(&file);

    // 如果没有读到文档结尾，而且没有出现错误
    while (!reader.atEnd()) {
        // 读取下一个记号，它返回记号的类型
        QXmlStreamReader::TokenType type = reader.readNext();

        // 下面便根据记号的类型来进行不同的输出
        if (type == QXmlStreamReader::StartDocument)
            qDebug() << reader.documentEncoding() << reader.documentVersion();

        if (type == QXmlStreamReader::StartElement) {
            qDebug() << "<" << reader.name() << ">";
            if (reader.attributes().hasAttribute("id"))
                qDebug() << reader.attributes().value("id");
        }

        if (type == QXmlStreamReader::EndElement)
            qDebug() << "</" << reader.name() << ">";

        if (type == QXmlStreamReader::Characters && !reader.isWhitespace())
            qDebug() << reader.text();
    }

    // 如果读取过程中出现错误，那么输出错误信息
    if (reader.hasError()) {
        qDebug() << "error: " << reader.errorString();
    }

    file.close();

    return a.exec();
}

写入数据

main.cpp

#include <QtCore/QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QXmlStreamWriter>
#include <QDebug>

int main(int argc,argv);

    QFile file("../myXmlStream/my2.xml");
    if (!file.open(QFile::WriteOnly | QFile::Text))
    {
        qDebug() << "Error: cannot open file";
        return 1;
    }

    QXmlStreamWriter stream(&file);
    stream.setAutoFormatting(true);
    stream.writeStartDocument();
    stream.writeStartElement("bookmark");
    stream.writeAttribute("href","http://qt.nokia.com/");
    stream.writeTextElement("title","Qt Home");
    stream.writeEndElement();
    stream.writeEndDocument();

    file.close();

    qDebug() << "write finished!";

    return a.exec();
}