QT中读取XML文件三种方式 的实例

#include "mainwindow.h" #include "ui_mainwindow.h" #include <QFile> #include <qmessagebox.h> #include <qdebug.h> MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); setWindowTitle(tr("XML Reader")); treeWidget = new QTreeWidget(this); QStringList headers; headers << "Items" << "Pages"; treeWidget->setHeaderLabels(headers); setCentralWidget(treeWidget); qDebug()<<QApplication::applicationDirPath(); } bool MainWindow::readFile(const QString &fileName) { QFile file(QApplication::applicationDirPath() + "/demo.xml"); if (!file.open(QFile::ReadOnly | QFile::Text)) { QMessageBox::critical(this, tr("Error"), tr("Cannot read file %1").arg(fileName)); return false; } reader.setDevice(&file); while (!reader.atEnd()) { if (reader.isStartElement()) { qDebug()<<"2222222222222222"; if (reader.name() == "bookindex") { readBookindexElement();//递归下降算法，层层读取 } else { reader.raiseError(tr("Not a valid book file")); } } else { qDebug()<<"111111111111111"; reader.readNext(); //循坏调用首次移动3次，后面移动一次 } } file.close(); if (reader.hasError()) { QMessageBox::critical(this, tr("Error"), tr("Failed to parse file %1").arg(fileName)); return false; } else if (file.error() != QFile::NoError) { QMessageBox::critical(this, tr("Error"), tr("Cannot read file %1").arg(fileName)); return false; } return true; } void MainWindow::readBookindexElement() { Q_ASSERT(reader.isStartElement() && reader.name() == "bookindex");//不是则会报错 reader.readNext(); // 读取下一个记号，它返回记号的类型 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 MainWindow::readEntryElement(QTreeWidgetItem *parent) { QTreeWidgetItem *item = new QTreeWidgetItem(parent); item->setText(0, reader.attributes().value("term").toString());//元素的属性 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 { skipUnknownElement(); } } else { reader.readNext(); } } } void MainWindow::readPageElement(QTreeWidgetItem *parent) { QString page = reader.readElementText(); if (reader.isEndElement()) { qDebug()<<"3333333333333333"; reader.readNext(); } QString allPages = parent->text(1); if (!allPages.isEmpty()) { allPages += ", "; } allPages += page; parent->setText(1, allPages); } void MainWindow::skipUnknownElement() { reader.readNext(); while (!reader.atEnd()) { if (reader.isEndElement()) { reader.readNext(); break; } if (reader.isStartElement()) { skipUnknownElement(); } else { reader.readNext(); } } } MainWindow::~MainWindow() { delete ui; }