Qt: QXMLStreamReader,读XML文件实例

主要接口：

1、​​T​​okenType QXmlStreamReader::readNext()

功能：读取下一个标记，并返回其类型。

主要的类型有：

enum QXmlStreamReader::TokenType

This enum specifies the type of token the reader just read.

2、bool QXmlStreamReader::atEnd() const

功能：判断是否已经读到XML文件的末尾，如果是，则返回true，否则返回false.

3、​​Q​​XmlStreamAttributes QXmlStreamReader::attributes() const

功能：返回​​StartElement​​.的属性。

4、​​Q​​StringRef QXmlStreamReader::name() const

功能：返回​​StartElement​​​, ​​EndElement​​的名称。

5、void QXmlStreamReader::raiseError(const ​​QString​​ &message = QString())

功能：提出一个错误，

需求：

使用QXMLStreamReader，读取XML文件，并使用XML文件初始化树形控件。

效果图：

源码：

main.cpp

#include <QApplication>
#include <QTreeWidget>
#include <QLabel>
#include <QHeaderView>
#include <QObject>
#include "xmlstreamreader.h"

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

    QTreeWidget *tree = new QTreeWidget;
    tree->setHeaderLabels( QStringList()<<"Term"<<"Pages"<<"Description" );
    tree->header()->setSectionResizeMode(QHeaderView::Stretch);
    tree->setWindowTitle(QObject::tr("XML Reader"));
    tree->show();

    QString fileName("in1.xml");
    XMLStreamReader w(tree);
    w.readFile(fileName);

    return a.exec();
}

XMLStreamReader.h

#ifndef XMLSTREAMREADER_H
#define XMLSTREAMREADER_H

#include <QXmlStreamReader>
#include <QTreeWidget>
#include <QTreeWidgetItem>

class XMLStreamReader
{

public:
    XMLStreamReader(QTreeWidget *tree);
    ~XMLStreamReader();
    bool readFile(const QString &fileName);

private:
    void readBookindexElement();
    void readEntryElement(QTreeWidgetItem *parent);
    void readPageElement(QTreeWidgetItem *parent);
    void skipUnknownElement();

    QTreeWidget *treeWidget;
    QXmlStreamReader reader;
};

#endif // XMLSTREAMREADER_H

XMLStreamReader.cpp

#include <QFile>
#include <QDebug>
#include "xmlstreamreader.h"

XMLStreamReader::XMLStreamReader(QTreeWidget *tree)
{
    treeWidget = tree;
}

XMLStreamReader::~XMLStreamReader()
{
    delete treeWidget;
}

bool XMLStreamReader::readFile(const QString &fileName)
{
    QFile file(fileName);
    if(!file.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug()<<"Open XML file Error";
        return false;
    }

    reader.setDevice(&file);
    while(!reader.atEnd())
    {
        if(reader.isStartElement())
        {
            if(reader.name() == "bookindex")
            {
                readBookindexElement();
            }
            else
            {
                Q_ASSERT(reader.isStartElement() && (reader.name() == "bookindex")); //断言
                reader.raiseError(QObject::tr("Not a BookIndex file"));
            }
        }
        else
        {
            reader.readNext();
        }
    }

    file.close();
    if(reader.hasError())
    {
        qDebug()<<reader.errorString();
        return false;
    }
    else if(file.error() != QFile::NoError)
    {
        qDebug()<<file.errorString();
        return false;
    }

    return true;
}

void XMLStreamReader::readBookindexElement()
{
    reader.readNext();
    while(!reader.atEnd())
    {
        if(reader.isEndElement())
        {
            reader.readNext();
            break;
        }

        if(reader.isStartElement())
        {
            if(reader.name() == "entry")
            {
                readEntryElement(treeWidget->invisibleRootItem());
            }
            else
            {
                skipUnknownElement();
            }
        }
        else
        {
            reader.readNext();
        }
    }
}

void XMLStreamReader::readEntryElement(QTreeWidgetItem *parent)
{
    QTreeWidgetItem *item = new QTreeWidgetItem(parent);
    item->setText(0,reader.attributes().value("term").toString());
    item->setText(2,reader.attributes().value("description").toString());
    reader.readNext();
    while(!reader.atEnd())
    {
        if(reader.isEndElement())
        {
            reader.readNext();
            break;
        }

        if(reader.isStartElement())
        {
            if(reader.name() == "entry")
            {
                readEntryElement(item);
            }
            else if(reader.name() == "page")
            {
                readPageElement(item);
            }
        }
        else
        {
            reader.readNext();
        }
    }
}

void XMLStreamReader::readPageElement(QTreeWidgetItem *parent)
{
    QString page = reader.readElementText();
    if(reader.isEndElement())
        reader.readNext();

    QString allPages = parent->text(1);
    if(!allPages.isEmpty())
        allPages +=", ";
    allPages += page;
    parent->setText(1,allPages);
}

void XMLStreamReader::skipUnknownElement()
{
    reader.readNext();
    while(!reader.atEnd())
    {
        if(reader.isEndElement())
        {
            reader.readNext();
            break;
        }

        if(reader.isStartElement())
        {
            skipUnknownElement();
        }
        else
        {
            reader.readNext();
        }
    }
}