Qt操作xml文件（增删改功能）

这个例子是在根据网上博客《Qt数据库（XML）》改写的一个操作XML的实现。

借鉴了很多里面的代码，大家可以结合上面的博客对照，相信你肯定会对XML的操作熟练起来。

我建立的是Qwidget项目，没有添加ui文件，输出内容都放在应用程序输出中（qDebug）。

XMLtest.pro文件代码：

#-------------------------------------------------
#
# Project created by QtCreator 2012-08-15T15:56:54
#
#-------------------------------------------------

QT       += core gui xml

TARGET = XMLtest
TEMPLATE = app


SOURCES += main.cpp\
        widget.cpp

HEADERS  += widget.h

widget.h文件代码：

#ifndef WIDGET_H
#define WIDGET_H

#include <QtGui/QWidget>
#include <QtCore>


class Widget : public QWidget
{
    Q_OBJECT
    
public:
    Widget(QWidget *parent = 0);
    ~Widget();

    void read_xml(QString filename);
    void create_xml(QString filename);
    void add_xmlnode(QString filename,QString rmt_name,QString ipa,QString ipb);
    void do_xml(const QString opt,QString filename);
private:
};

#endif // WIDGET_H

widget.cpp文件代码：

#include "widget.h"
#include "qfile.h"
#include "qdebug.h"
#include <QDomDocument>
#include "qtextcodec.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    QTextCodec::setCodecForCStrings(QTextCodec::codecForName("GB2312"));

    QFile *file;
    QString  filename = "config.xml";
    if(file->exists("config.xml"))
    {
        read_xml(filename);
    }
    else
    {
        create_xml(filename);
    }

    add_xmlnode(filename,"remote1","127.0.0.1","192.168.1.199");
    do_xml("update",filename);
}

Widget::~Widget()
{
    
}

void Widget::do_xml(const QString opt,QString filename)
{
    QFile file(filename);
    if(!file.open(QIODevice::ReadOnly | QIODevice::Text))
    {
        qDebug() << "open for do erro";
        file.close();
    }

    QDomDocument doc;
    if(!doc.setContent(&file))
     {
        qDebug() << "setcontent for do error";
        file.close();
    }
    file.close();
    QDomNodeList lists = doc.elementsByTagName("remote");
    QDomElement ele = lists.at(1).toElement();
    if(ele.attribute(tr("id")) == "3")
    {
        if("delete" == opt || "update" == opt)
        {
            QDomElement root = doc.documentElement();
            if("delete" == opt)
            {
                root.removeChild(lists.at(1));
                qDebug() << "remove ok !";
            }
            else
            {
                QDomNodeList child=lists.at(1).childNodes();
                child.at(0).toElement().firstChild().setNodeValue("namechanged");
                child.at(1).toElement().firstChild().setNodeValue("ipachanged");
                child.at(2).toElement().firstChild().setNodeValue("ipbchanged");
                qDebug() << "modify ok !";
            }
            if(!file.open(QIODevice::WriteOnly | QIODevice::Text))
            {
                qDebug() << "open for remove error!";
            }
            QTextStream out(&file);
            doc.save(out,4);
            file.close();

        }
    }
}

void Widget::add_xmlnode(QString filename,QString rmt_name, QString ipa, QString ipb)
{
    QFile file(filename);
    if (!file.open(QIODevice::ReadOnly | QFile::Text)) {
        qDebug()<<"open for add error..." ;
    }
    QDomDocument doc;
    QString errorStr;
    int errorLine;
    int errorColumn;

    if (!doc.setContent(&file, false, &errorStr, &errorLine, &errorColumn)) {
        qDebug()<<"add setcontent error..." ;
        file.close();
    }
    //QDomNode node = doc.firstChild();
    file.close();
    QDomElement root = doc.documentElement();
    if(root.isNull())
    {
        root = doc.createElement("ipconfig");
    }
    QDomElement element_root = doc.createElement(tr("remote"));
    QDomAttr attr_id = doc.createAttribute(tr("id"));
    QDomElement element_rmt = doc.createElement(tr("rmt_name"));
    QDomElement element_ipa = doc.createElement(tr("ipa"));
    QDomElement element_ipb = doc.createElement(tr("ipb"));
    QString str_id;
    if(root.lastChild().isNull())
    {
        str_id = "1";
        attr_id.setValue(str_id);
    }
    else
    {
        str_id = root.lastChild().toElement().attribute(tr("id"));
        int count = str_id.toInt()+1;
        attr_id.setValue(QString::number(count));
    }
    QDomText text;
    text =doc.createTextNode(rmt_name);
    element_rmt.appendChild(text);
    text = doc.createTextNode(ipa);
    element_ipa.appendChild(text);
    text = doc.createTextNode(ipb);
    element_ipb.appendChild(text);
    text.clear();
    element_root.appendChild(element_rmt);
    element_root.appendChild(element_ipa);
    element_root.appendChild(element_ipb);
    element_root.setAttributeNode(attr_id);
    root.appendChild(element_root);

    if(!file.open(QIODevice::WriteOnly|QIODevice::Append))
        qDebug() << "open for add error!";
    QTextStream out(&file);
    doc.save(out,4);
    file.close();
}

void Widget::read_xml(QString filename)
{
    QFile file(filename);
    if (!file.open(QIODevice::ReadOnly | QFile::Text)) {
        qDebug()<<"open for read error..." ;
    }
    QString errorStr;
    int errorLine;
    int errorColumn;

    QDomDocument doc;
    if (!doc.setContent(&file, false, &errorStr, &errorLine, &errorColumn)) {
        qDebug()<<"setcontent error..." ;
        file.close();
    }
    file.close();
    QDomElement root = doc.documentElement();
    if (root.tagName() != "ipconfig") {
       qDebug()<<"root.tagname != ipconfig..." ;
    }
    QDomNode node = root.firstChild();
    while(!node.isNull())
    {
        if(node.isElement())
        {
            QDomElement element = node.toElement();
            qDebug() << qPrintable(element.tagName())<<qPrintable(element.attribute("id"));
            QDomNodeList list = element.childNodes();
            for(int i = 0;i < list.count();i++)
            {
                QDomNode nodechild = list.at(i);
                if(nodechild.isElement())
                {
                    qDebug() << "    " << qPrintable(nodechild.toElement().tagName()) << qPrintable(nodechild.toElement().text());
                }
            }
        }
        node = node.nextSibling();
    }
}

void Widget::create_xml(QString filename)
{
    QFile file(filename);
    file.open(QIODevice::ReadWrite);
    QDomDocument doc;
    QDomProcessingInstruction instruction;
    instruction = doc.createProcessingInstruction("xml","version=\"1.0\" encoding=\"GB2312\"");
    doc.appendChild(instruction);
    QDomElement root = doc.createElement("ipconfig");

    doc.appendChild(root);
    QDomText text = doc.createTextNode("");
    root.appendChild(text);
    QTextStream out(&file);
    doc.save(out,4);
    file.close();
}

main.cpp文件代码：

#include <QtGui/QApplication>
#include "widget.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    
    return a.exec();
}

XML文件结构：

<?xml version='1.0' encoding='GB2312'?>
<ipconfig>
    <remote id="1">
        <rmt_name>remote1</rmt_name>
        <ipa>127.0.0.1</ipa>
        <ipb>192.168.1.199</ipb>
    </remote>
    <remote id="3">
        <rmt_name>namechanged</rmt_name>
        <ipa>ipachanged</ipa>
        <ipb>ipbchanged</ipb>
    </remote>
    <remote id="4">
        <rmt_name>remote1</rmt_name>
        <ipa>127.0.0.1</ipa>
        <ipb>192.168.1.199</ipb>
    </remote>
    <remote id="5">
        <rmt_name>remote1</rmt_name>
        <ipa>127.0.0.1</ipa>
        <ipb>192.168.1.199</ipb>
    </remote>
    <remote id="6">
        <rmt_name>remote1</rmt_name>
        <ipa>127.0.0.1</ipa>
        <ipb>192.168.1.199</ipb>
    </remote>
    <remote id="7">
        <rmt_name>remote1</rmt_name>
        <ipa>127.0.0.1</ipa>
        <ipb>192.168.1.199</ipb>
    </remote>
    <remote id="8">
        <rmt_name>remote1</rmt_name>
        <ipa>127.0.0.1</ipa>
        <ipb>192.168.1.199</ipb>
    </remote>
</ipconfig>

应用程序输出：

remote 1

rmt_name remote1

ipa 127.0.0.1

ipb 192.168.1.199

remote 3

rmt_name remote1

ipa 127.0.0.1

ipb 192.168.1.199

remote 4

rmt_name remote1

ipa 127.0.0.1

ipb 192.168.1.199

remote 5

rmt_name remote1

ipa 127.0.0.1

ipb 192.168.1.199

remote 6

rmt_name remote1

ipa 127.0.0.1

ipb 192.168.1.199

remote 7

rmt_name remote1

ipa 127.0.0.1

ipb 192.168.1.199

modify ok !