QT-实例-用qt做一个记事本，完成记事本所有简单的功能

用qt纯代码做一个记事本，并将所有简单的功能实现

网上有很多做记事本的例子都是用的是designer设计师操作ui界面来实现的，包括官方的notepad实例也是这样子，所以决定用纯代码的方式，做一个记事本的小例子，并将所有简单的功能实现出来

1.新建一个基类为mainwindow的工程，取消ui界面的创建

2.在工程中添加资源文件，用以存放图片，图片的尺寸最好是符合菜单工具栏大小的，推荐32*32大小

3.h头文件中添加所需要的控件头文件

#include <QMenu>
#include <QMenuBar>
#include <QAction>
#include <QToolBar>
#include <QLineEdit>
#include <QTextEdit>
#include <QVBoxLayout>

然后在头文件中初始化声明

private:

    //新建
    QMenu *fileMenu, *editMenu, *helpMenu;
    QToolBar *fileToolBar;
    QToolBar *editToolBar;        //新建两个工具栏，用以存放四个菜单动作
    QAction *newAct;
    QAction *openAct;
    QAction *saveAct;
    QAction *saveasAct;
    QAction *printAct;
    QAction *cutAct;
    QAction *copyAct;
    QAction *pasteAct;
    QAction *undoAct;
    QAction *redoAct;
    QAction *aboutQtAct;
    QAction *exitAct;
    QTextEdit *textEdit;
    QLineEdit *lineEdit;
    QVBoxLayout *vboxlayout;

初始化所需要的槽函数，用以实现各种功能,槽函数的名字最好取来简单易懂，让自己一眼就知道是什么意思

private slots:
    void newFile();
    void openFile();
    void saveFile();
    void saveasFile();
    void printFile();
    void cutAction();
    void copyAction();
    void pasteAction();
    void undoAction();
    void redoAction();
    void exitAction();

4.cpp文件中的操作

在cpp文件中添加相应的文件操作以及所需要的头文件，文件操作的相关流程在上一篇博客里使用QFile文件操作

#include <QMessageBox>
#include <QFile>
#include <QFileDialog>
#include <QTextStream>
#include <QIcon>

对于菜单栏和工具栏的实例化在ui界面的实现方法里是直接通过拖动创建的，因为我这里用的是纯代码写的，可能有些繁琐，但是理解起来更简单，有助于理解界面编程的精髓以及项目的移植，所以倡导多用纯代码写界面。相关的代码实现如下

	this->resize(500,400);
    this->setWindowTitle("记事本");
    this->setWindowIcon(QIcon(":/images/file/notepad.png"));        //设置应用显示图标

    //实例菜单和控件
    fileMenu = new QMenu(this);
    editMenu = new QMenu(this);
    helpMenu = new QMenu(this);
    textEdit = new QTextEdit(this);
    vboxlayout = new QVBoxLayout(this);
    this->setCentralWidget(textEdit);


    //填充菜单子节点
    newAct = new QAction(QIcon( ":/images/file/new_file.png" ), tr( "新建" ), this );
    newAct->setShortcut(tr("Ctrl+N" ));       					 //快捷键
    newAct->setStatusTip(tr("新建文件" ));     					 //底部状态提示
    openAct = new QAction(QIcon( ":/images/file/open_file.png" ), tr( "打开" ), this );
    openAct->setShortcut(tr("Ctrl+O" ));
    openAct->setStatusTip(tr("打开文件" ));
    saveAct = new QAction(QIcon( ":/images/file/save_file.png" ), tr( "保存" ), this );
    saveAct->setShortcut(tr("Ctrl+S" ));
    saveAct->setStatusTip(tr("保存文件" ));
    saveasAct = new QAction(QIcon( ":/images/file/save_as.png" ), tr( "另存为" ), this );
    saveasAct->setShortcut(tr("Ctrl+Shift+S" ));
    saveasAct->setStatusTip(tr("另存为文件" ));
    printAct = new QAction(QIcon( ":/images/file/print.png" ), tr( "打印" ), this );
    printAct->setShortcut(tr("Ctrl+P" ));
    printAct->setStatusTip(tr("打印" ));
    exitAct = new QAction(QIcon( ":/images/file/exit.png" ), tr( "退出" ), this );
    exitAct->setShortcut(tr("Ctrl+E"));
    exitAct->setStatusTip(tr("退出"));

    //信号与槽
    connect(newAct, SIGNAL(triggered()), this, SLOT(newFile()));
    connect(openAct,SIGNAL(triggered()),this,SLOT(openFile()));
    connect(saveAct,SIGNAL(triggered()),this,SLOT(saveFile()));
    connect(saveasAct,SIGNAL(triggered()),this,SLOT(saveasFile()));
    connect(printAct,SIGNAL(triggered()),this,SLOT(printFile()));

    cutAct = new QAction(QIcon( ":/images/file/cut.png" ), tr( "剪切" ), this );
    cutAct->setShortcut(tr("Ctrl+X" ));
    cutAct->setStatusTip(tr("剪切内容" ));
    copyAct = new QAction(QIcon( ":/images/file/复制.png" ), tr( "复制" ), this );
    copyAct->setShortcut(tr("Ctrl+C" ));
    copyAct->setStatusTip(tr("复制内容" ));
    pasteAct = new QAction(QIcon( ":/images/file/粘贴.png" ), tr( "粘贴" ), this );
    pasteAct->setShortcut(tr("Ctrl+V" ));
    pasteAct->setStatusTip(tr("粘贴内容" ));
    undoAct = new QAction(QIcon( ":/images/file/undo.png" ), tr( "向后" ), this );
    undoAct->setShortcut(tr("Ctrl+Z" ));
    undoAct->setStatusTip(tr("向后一步" ));
    redoAct = new QAction(QIcon( ":/images/file/redo.png" ), tr( "向前" ), this );
    redoAct->setShortcut(tr("Ctrl+Y" ));
    redoAct->setStatusTip(tr("向前一步" ));
    aboutQtAct = new QAction(QIcon(":/images/file/about.png"),tr( "关于 Qt" ), this );
    aboutQtAct->setStatusTip(tr("关于 Qt 信息" ));

    //信号与槽
    connect(copyAct, SIGNAL(triggered()), this, SLOT(copyAction()));
    connect(cutAct, SIGNAL(triggered()), this, SLOT(cutAction()));
    connect(pasteAct, SIGNAL(triggered()), this, SLOT(pasteAction()));
    connect(undoAct, SIGNAL(triggered()), this, SLOT(undoAction()));
    connect(redoAct, SIGNAL(triggered()), this, SLOT(redoAction()));
    connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
    connect(exitAct, SIGNAL(triggered()), this, SLOT(exitAction()));


    //填充菜单
    fileMenu = menuBar()->addMenu(tr( "文件" ));
    fileMenu->addAction(newAct);
    fileMenu->addAction(openAct);
    fileMenu->addAction(saveAct);
    fileMenu->addAction(saveasAct);
    fileMenu->addAction(exitAct);
    fileMenu->addSeparator();

    editMenu = menuBar()->addMenu(tr("编辑" ));
    editMenu->addAction(cutAct);
    editMenu->addAction(copyAct);
    editMenu->addAction(pasteAct);
    editMenu->addAction(undoAct);
    editMenu->addAction(redoAct);
    menuBar()->addSeparator();

    helpMenu = menuBar()->addMenu(tr("帮助" ));
    helpMenu->addAction(aboutQtAct);

    //toolBar 工具条
    //fileTooBar添加
    fileToolBar = addToolBar(tr("新建"));     //右键添加改变
    fileToolBar->addAction(newAct);
    fileToolBar->addAction(openAct);
    fileToolBar->addAction(saveAct);
    fileToolBar->addAction(saveasAct);
    fileToolBar->addAction(printAct);
    //editToolBar添加
    editToolBar = addToolBar(tr("修改"));
    editToolBar->addAction(cutAct);
    editToolBar->addAction(copyAct);
    editToolBar->addAction(pasteAct);
    editToolBar->addAction(undoAct);
    editToolBar->addAction(redoAct);
    editToolBar->addAction(exitAct);


}

MainWindow::~MainWindow()
{
    delete ui;
}

/*
void MainWindow::showMainwindow2()
{
    w2.show();
}
*/

/*槽函数实现*/

//子菜单事件
void MainWindow::newFile()
{
    /*
     *
    QMessageBox::warning(this,tr("Warning"),
    tr("创建新文件？"),
    QMessageBox::Yes | QMessageBox::Default,
    QMessageBox::No);
    *
    */
    currentFile.clear();
    textEdit->setText(QString());
}

void MainWindow::openFile()
{
    QString fileName = QFileDialog::getOpenFileName(this, "打开文件");
    QFile file(fileName);
    currentFile = fileName;
    if (!file.open(QIODevice::ReadOnly | QFile::Text)) {
        QMessageBox::warning(this, "警告", "无法打开文件: " + file.errorString());
        return;
    }
    setWindowTitle(fileName);
    QTextStream in(&file);
    QString text = in.readAll();
    textEdit->setText(text);
    file.close();
}

void MainWindow::saveFile()
{
    QString fileName;
    // 若没有文件,重新创建一个
    if (currentFile.isEmpty()) {
        fileName = QFileDialog::getSaveFileName(this, "Save");
        currentFile = fileName;
    } else {
        fileName = currentFile;
    }
    QFile file(fileName);
    if (!file.open(QIODevice::WriteOnly | QFile::Text)) {
        QMessageBox::warning(this, "警告", "无法打开文件: " + file.errorString());
        return;
    }
    setWindowTitle(fileName);
    QTextStream out(&file);
    QString text = textEdit->toPlainText();
    out << text;
    file.close();
}

void MainWindow::saveasFile()
{
    QString fileName = QFileDialog::getSaveFileName(this, "另存为");
    QFile file(fileName);

    if (!file.open(QFile::WriteOnly | QFile::Text)) {
        QMessageBox::warning(this, "警告", "无法打开文件: " + file.errorString());
        return;
    }
    currentFile = fileName;
    setWindowTitle(fileName);
    QTextStream out(&file);
    QString text = textEdit->toPlainText();
    out << text;
    file.close();
}

void MainWindow::printFile()
{
    //暂时空
    /*
#if QT_CONFIG(printer)
    QPrinter printDev;
#if QT_CONFIG(printdialog)
    QPrintDialog dialog(&printDev, this);
    if (dialog.exec() == QDialog::Rejected)
        return;
#endif // QT_CONFIG(printdialog)
    ui->textEdit->print(&printDev);
#endif // QT_CONFIG(printer)

*/
}



void MainWindow::cutAction()
{
    textEdit->cut();
}

void MainWindow::pasteAction()
{
    textEdit->paste();
}

void MainWindow::copyAction()
{
    textEdit->copy();
}

void MainWindow::undoAction()
{
    textEdit->undo();
}

void MainWindow::redoAction()
{
    textEdit->redo();
}

void MainWindow::exitAction()
{
    this->close();
}

敲出来的代码感觉很有成就感，当然，在大佬面前这种东西不值一提（萌新哭唧唧┭┮﹏┭┮），效果实现如下

记事本的所有简单的功能就这样实现了。这里没有对界面部分做进一步的优化，还是能让人感觉到Qt的魅力以及界面编程的魅力。附上文件下载链接Qt纯代码记事本