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 !