Qt之菜单栏中文件的写入、打开、保存

标签：return Qt QMessageBox QAction 写入 fileName file 菜单栏 MainWindow

在常见的记事本中，通常都有打开文件，写入文件、保存文件等功能，今天就用Qt来写一下记事本的打开、写入、保存等功能

一、创建菜单栏

 　 QMenu *fileMenu = menuBar()->addMenu("File");
    QToolBar *fileToolBar = addToolBar("File");

    QAction *newAct = new QAction(QIcon(":/images/new.png"), "New", this);
    //添加快捷键
    newAct->setShortcuts(QKeySequence::New);
    //状态栏提示
    newAct->setStatusTip(tr("Create a new file"));
    connect(newAct, &QAction::triggered, this, &MainWindow::newFile);

    //添加菜单栏
    fileMenu->addAction(newAct);
    //添加工具栏
    fileToolBar->addAction(newAct);

    QAction *openAct = new QAction(QIcon(":/images/open.png"), "Open...", this);
    openAct->setShortcuts(QKeySequence::Open);
    openAct->setStatusTip("Open an existing file");
    connect(openAct, &QAction::triggered, this, &MainWindow::open);
    fileMenu->addAction(openAct);
    fileToolBar->addAction(openAct);

    QAction *saveAct = new QAction(QIcon(":/images/save.png"), "Save", this);
    saveAct->setShortcuts(QKeySequence::Save);
    saveAct->setStatusTip("Save the document to disk");
    connect(saveAct, &QAction::triggered, this, &MainWindow::save);
    fileMenu->addAction(saveAct);
    fileToolBar->addAction(saveAct);

    QAction *saveAsAct = fileMenu->addAction("Save As...", this, &MainWindow::saveAs, QKeySequence::SaveAs);
    saveAsAct->setStatusTip("Save the document under a new name");

    //添加分割线
    fileMenu->addSeparator();

    QAction *exitAct = fileMenu->addAction("Exit", this, &QWidget::close);
    exitAct->setShortcuts(QKeySequence::Quit);
    exitAct->setStatusTip("Exit the application");

    //创建状态栏
    statusBar()->showMessage(tr("Ready"));

 

 

 

 

 三、文件的写入并保存

bool MainWindow::save()
{
    if (curFile.isEmpty()) {
        return saveAs();
    } else {
        return saveFile(curFile);
    }
}

bool MainWindow::saveAs()
{
    QFileDialog dialog(this);
    dialog.setWindowModality(Qt::WindowModal);
    dialog.setAcceptMode(QFileDialog::AcceptSave);
    if (dialog.exec() != QDialog::Accepted)
        return false;
    return saveFile(dialog.selectedFiles().first());
}

bool MainWindow::saveFile(const QString &fileName)
{
    QString errorMessage;

    QGuiApplication::setOverrideCursor(Qt::WaitCursor);
    QSaveFile file(fileName);
    if (file.open(QFile::WriteOnly | QFile::Text)) {
        QTextStream out(&file);
        out << textEdit->toPlainText();
        if (!file.commit()) {
            errorMessage = tr("Cannot write file %1:\n%2.")
                           .arg(QDir::toNativeSeparators(fileName), file.errorString());
        }
    } else {
        errorMessage = tr("Cannot open file %1 for writing:\n%2.")
                       .arg(QDir::toNativeSeparators(fileName), file.errorString());
    }
    QGuiApplication::restoreOverrideCursor();

    if (!errorMessage.isEmpty()) {
        QMessageBox::warning(this, "error", errorMessage);
        return false;
    }

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File saved"), 2000);
    return true;
}

三、打开新文件

bool MainWindow::maybeSave()
{
    //监测文本框中的内容是否修改，如何修改则保存
    if (!textEdit->document()->isModified())
        return true;
    
    const QMessageBox::StandardButton ret
        = QMessageBox::warning(this, "error",
                               "The document has been modified.\n"
                                  "Do you want to save your changes?",
                               QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
    switch (ret) {
    case QMessageBox::Save:
        return save();
    case QMessageBox::Cancel:
        return false;
    default:
        break;
    }
    return true;
}

void MainWindow::open()
{
    if (maybeSave()) {
        QString fileName = QFileDialog::getOpenFileName(this);
        if (!fileName.isEmpty())
            loadFile(fileName);
    }
}

void MainWindow::loadFile(const QString &fileName)
{
    QFile file(fileName);
    if (!file.open(QFile::ReadOnly | QFile::Text)) {
        QMessageBox::warning(this, tr("Application"),
                             tr("Cannot read file %1:\n%2.")
                             .arg(QDir::toNativeSeparators(fileName), file.errorString()));
        return;
    }

    QTextStream in(&file);
    QGuiApplication::setOverrideCursor(Qt::WaitCursor);
    textEdit->setPlainText(in.readAll());
    QGuiApplication::restoreOverrideCursor();

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File loaded"), 2000);
}

 

标签：return,Qt,QMessageBox,QAction,写入,fileName,file,菜单栏,MainWindow
From： https://www.cnblogs.com/QingYiShouJiuRen/p/16849551.html