Qt的文本文件读写

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <boost/scoped_ptr.hpp>
using namespace boost;


class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void readFile(const QString& fileName);
    void writeFile(const QString& fileName);
public slots:
    void open();
    void save();
    void saveAs();
    void close();
    void quit();
protected:
    void dragEnterEvent(QDragEnterEvent *);
    void dropEvent(QDropEvent *);
private:
    class MainWindowUi;
    scoped_ptr<MainWindowUi> mui;
    class MainWindowData;
    scoped_ptr<MainWindowData> mData;
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include <QFileDialog>
#include <QString>
#include <QTextStream>
#include <QCloseEvent>
#include <QDesktopWidget>
#include <QUrl>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <iostream>
using namespace std;

class MainWindow::MainWindowData{
public:
    QString mFileName;
    QString mText;
    QFile mFile;
    QTextStream mStream;
};

class MainWindow::MainWindowUi:public Ui::MainWindow{
public:
    QFileDialog* mFileDialog;
public:
    MainWindowUi(){

    }
};

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    mui.reset(new MainWindowUi);
    mui->setupUi(this);
    mData.reset(new MainWindowData);
    mui->mFileDialog = new QFileDialog(this);
    mui->textEdit->setAcceptDrops(false);
    setAcceptDrops(true);
    //把所有action与对应的槽相连
    connect(mui->action_open, SIGNAL(triggered()), this, SLOT(open()));
    connect(mui->action_save, SIGNAL(triggered()), this ,SLOT(save()));
    connect(mui->actionSave_As, SIGNAL(triggered()), this ,SLOT(saveAs()));
    connect(mui->action_close,SIGNAL(triggered()), this, SLOT(close()));
    connect(mui->action_quit, SIGNAL(triggered()), this, SLOT(quit()));
    //放到屏幕中间
    int screenCenterX =(QDesktopWidget().screenGeometry().width()-geometry().width())/2;
    int screenCenterY =(QDesktopWidget().screenGeometry().height()-geometry().height())/2;
    //宽和高就用设计器中设置的吧
    setGeometry(screenCenterX,screenCenterY,width(),height());
}

/*
  根据文件名读文本文件
*/
void MainWindow::readFile(const QString &fileName){
    mData->mFile.setFileName(fileName);
    if(!mData->mFile.open(QIODevice::ReadOnly|QIODevice::Text))
        return;
    //怕文件太大，一行一行地读
    mData->mStream.setDevice(&mData->mFile);
    QString line = mData->mStream.readLine();
    while(not line.isNull()){
        mData->mText.append(line).append("\n");
        line = mData->mStream.readLine();
    }
    //读完得关了它,最好一开始就写上，我在测试writeFile能否读text时没写后面的代码，
    //结果一关程序就把我的源码清空了2个才发现,悲剧啊...
    mData->mFile.close();
    mui->textEdit->clear();
    mui->textEdit->setText(mData->mText);
}

/*
  根据文件名写文本文件
*/
void MainWindow::writeFile(const QString &fileName){
    mData->mFile.setFileName(fileName);
    if(not mData->mFile.open(QIODevice::WriteOnly|QIODevice::Truncate))
        return;//can not write
    mData->mStream.setDevice(&mData->mFile);
    QStringList currentTextList = mui->textEdit->toPlainText().split("\n");
    foreach(QString str,currentTextList){
        mData->mStream << str << "\n";
    }
    mData->mFile.close();
}

void MainWindow::open(){
    mData->mFileName = mui->mFileDialog->getOpenFileName(this,tr("Open File"),//这个对话框的标题
                                                    "/home/xiangjie/code/unix/T1/",
                                                    tr("files(*.c *.cc *.cpp *.txt)"));//这里相当于是过滤器
    readFile(mData->mFileName);
}

/*
  保存
  */
void MainWindow::save(){
    if(mData->mFileName.isNull())
        return;
    writeFile(mData->mFileName);
}

/*
  另存为
  */
void MainWindow::saveAs(){
    mData->mFileName = mui->mFileDialog->getSaveFileName(this,tr("Save File"),
                                                         "/home/xiangjie/code",
                                                         tr("files(*.c *.cc *.cpp *.txt)"));
    save();
}

/*
  清空textEdit和fileName
 */
void MainWindow::close(){
    mui->textEdit->clear();
    mData->mFileName.clear();
}

/*
  关闭所有窗口
*/
void MainWindow::quit(){
    qApp->closeAllWindows();
}

/*
 拖放
 */
void MainWindow::dragEnterEvent(QDragEnterEvent *event){
    if(event->mimeData()->hasFormat("text/uri-list"))
        event->acceptProposedAction();
}

void MainWindow::dropEvent(QDropEvent *event){
    QList<QUrl> urls = event->mimeData()->urls();
    if(urls.isEmpty())
        return;
    QString fileName = urls.first().toLocalFile();
    if(fileName.isEmpty())
        return;
    readFile(fileName);
    setWindowTitle(tr("%1-%2").arg(fileName).arg(tr("Drag file")));
}

MainWindow::~MainWindow()
{
}

main.cpp

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

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