用 Qt 读取 XML 文件的方法
原文：https://blog.csdn.net/liyuanbhu/article/details/44062479
XML 是可扩展标记语言（Extensible Markup Language）的缩写。XML 文件由内容和标记组成，通过以标记包围内容的方式将大部分内容包含在元素中。
Qt 中提供了多种读取XML文件的方法，这里简单的记录一下用 QDomDocument 读取的步骤。为什么使用QDomDocument 呢，因为XML 本身就是一以树状结构组织数据的，而DOM 也是将数据组织为树状结构，最适合直观地展示XML数据。
下面的代码是Qt 帮助文件中自带的例子代码：
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QDomDocument doc("mydocument");
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QFile file("mydocument.xml");
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if (!file.open(QIODevice::ReadOnly))
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return;
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if (!doc.setContent(&file))
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{
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file.close();
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return;
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}
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file.close();
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// print out the element names of all elements that are direct children
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// of the outermost element.
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QDomElement docElem = doc.documentElement();
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QDomNode n = docElem.firstChild();
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while (!n.isNull())
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{
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QDomElement e = n.toElement();
// try to convert the node to an element.
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if (!e.isNull())
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{
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cout << qPrintable(e.tagName()) <<
endl;
// the node really is an element.
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}
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n = n.nextSibling();
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}
如果xml有多层，那么可以递归的去读取。我写了小程序将xml 的的数据读入到一个树型列表控件中。下面是核心的代码：
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#ifndef DIALOG_H
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#define DIALOG_H
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#include
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#include
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namespace Ui {
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class Dialog;
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}
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class QTreeWidgetItem;
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class Dialog :
public QDialog
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{
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Q_OBJECT
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public:
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explicit Dialog(QWidget *parent = 0);
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void listDom(QDomElement& docElem, QTreeWidgetItem* pItem);
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void openXML(QString fileName);
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~Dialog();
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private:
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Ui::Dialog *ui;
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private slots:
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void openFile();
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};
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#endif // DIALOG_H
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#include "dialog.h"
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#include "ui_dialog.h"
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#include
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Dialog::Dialog(QWidget *parent) :
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QDialog(parent),
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ui(
new Ui::Dialog)
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{
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ui->setupUi(
this);
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connect(ui->pushButtonOpen, SIGNAL(clicked()),
this, SLOT(openFile()));
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ui->treeWidget->setColumnCount(
2);
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ui->treeWidget->setColumnWidth(
0,
400);
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setWindowFlags(Qt::Dialog | Qt::WindowMaximizeButtonHint | Qt::WindowMinimizeButtonHint);
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showMaximized();
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}
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void Dialog::openXML(QString fileName)
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{
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QFile file(fileName);
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if(file.open(QIODevice::ReadOnly))
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{
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QDomDocument dom("WCM");
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if (dom.setContent(&file))
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{
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ui->treeWidget->clear();
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QDomElement docElem = dom.documentElement();
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listDom(docElem,
NULL);
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}
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}
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file.close();
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}
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void Dialog::openFile()
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{
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QString fileName = QFileDialog::getOpenFileName(
this, tr(
"Open XML File"),
"c:/", tr(
"XML Files (*.xml)"));
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if(!fileName.isEmpty())
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{
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openXML( fileName );
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}
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}
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Dialog::~Dialog()
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{
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delete ui;
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}
-
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void Dialog::listDom(QDomElement& docElem, QTreeWidgetItem * pItem)
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{
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QDomNode node = docElem.firstChild();
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if(node.toElement().isNull())
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{
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pItem->setText (
1, docElem.text());
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}
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while(!node.isNull())
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{
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QDomElement element = node.toElement();
// try to convert the node to an element.
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if( !element.isNull() )
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{
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QTreeWidgetItem *item;
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if( pItem )
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{
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item =
new QTreeWidgetItem(pItem);
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}
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else
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{
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item =
new QTreeWidgetItem(ui->treeWidget);
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}
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item->setText(
0, element.tagName());
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listDom(element, item);
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if( pItem )
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{
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pItem->addChild(item);
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}
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else
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{
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ui->treeWidget->addTopLevelItem(item);
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}
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}
-
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node = node.nextSibling();
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}
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return;
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}
下面是个测试 xml 文件：
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xml version="1.0" encoding="UTF-8"?>
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<recipe type="dessert">
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<recipename cuisine="american" servings="1">Ice Cream Sundae
recipename>
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<ingredlist>
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<listitem>
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<quantity units="cups">0.5
quantity>
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<itemdescription>vanilla ice cream
itemdescription>
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listitem>
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<listitem>
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<quantity units="tablespoons">3
quantity>
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<itemdescription>chocolate syrup or chocolate fudge
itemdescription>
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listitem>
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<listitem>
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<quantity units="tablespoons">1
quantity>
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<itemdescription>nuts
itemdescription>
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listitem>
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<listitem>
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<quantity units="each">1
quantity>
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<itemdescription>cherry
itemdescription>
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listitem>
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ingredlist>
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<utensils>
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<listitem>
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<quantity units="each">1
quantity>
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<utensilname>bowl
utensilname>
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listitem>
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<listitem>
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<quantity units="each">1
quantity>
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<utensilname>spoons
utensilname>
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listitem>
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<listitem>
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<quantity units="each">1
quantity>
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<utensilname>ice cream scoop
utensilname>
-
listitem>
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utensils>
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<directions>
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<step>Using ice cream scoop, place vanilla ice cream into bowl.
step>
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<step>Drizzle chocolate syrup or chocolate fudge over the ice cream.
step>
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<step>Sprinkle nuts over the mound of chocolate and ice cream.
step>
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<step>Place cherry on top of mound with stem pointing upward.
step>
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<step>Serve.
step>
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directions>
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<variations>
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<option>Replace nuts with raisins.
option>
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<option>Use chocolate ice cream instead of vanilla ice cream.
option>
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variations>
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<preptime>5 minutes
preptime>
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recipe>