Qt菜单、文件、信号与槽最简单程序

#ifndef MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>

class QTextEdit;

class MainWindow : public QMainWindow

{

    Q_OBJECT

public:

    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();

private slots:

    void openFile();

    void saveFile();

private:

    QAction *openAction;

    QAction *saveAction;

    QTextEdit *textEdit;

};

#endif// MAINWINDOW_H

#include <QtGui>

#include <QtWidgets>

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent)

{

    openAction = new QAction(QIcon(":/images/file-open"), tr("&Open..."), this);

    openAction->setShortcuts(QKeySequence::Open);

    openAction->setStatusTip(tr("Open an existing file"));

    connect(openAction, &QAction::triggered, this, &MainWindow::openFile);

    saveAction = new QAction(QIcon(":/images/file-save"), tr("&Save..."), this);

    saveAction->setShortcuts(QKeySequence::Save);

    saveAction->setStatusTip(tr("Save a new file"));

    connect(saveAction, &QAction::triggered, this, &MainWindow::saveFile);

    QMenu *file = menuBar()->addMenu(tr("&File"));

    file->addAction(openAction);

    file->addAction(saveAction);

    QToolBar *toolBar = addToolBar(tr("&File"));

    toolBar->addAction(openAction);

    toolBar->addAction(saveAction);

    textEdit = new QTextEdit(this);

    setCentralWidget(textEdit);

}

MainWindow::~MainWindow()

{

}

void MainWindow::openFile()

{

    QString path = QFileDialog::getOpenFileName(this, tr("Open File"), ".", tr("Text Files(*.txt)"));

    if(!path.isEmpty())

    {

        QFile file(path);

        if (!file.open(QIODevice::ReadOnly | QIODevice::Text))

        {

            QMessageBox::warning(this, tr("Read File"), tr("Cannot open file:\n%1").arg(path));

            return;

        }

        QTextStream in(&file);

        textEdit->setText(in.readAll());

        file.close();

    }

    else

    {

        QMessageBox::warning(this, tr("Path"), tr("You did not select any file."));

    }

}

void MainWindow::saveFile()

{

    QString path = QFileDialog::getSaveFileName(this, tr("Save File"), ".", tr("Text Files(*.txt)"));

    if(!path.isEmpty())

    {

        QFile file(path);

        if (!file.open(QIODevice::WriteOnly | QIODevice::Text))

        {

            QMessageBox::warning(this, tr("Write File"), tr("Cannot open file:\n%1").arg(path));

            return;

        }

        QTextStream out(&file);

        out << textEdit->toPlainText();

        file.close();

    }

    else

    {

        QMessageBox::warning(this, tr("Path"), tr("You did not select any file."));

    }

}

#include <QApplication>

#include "mainwindow.h"

int main(int argc, char *argv[])

{

    QApplication a(argc, argv);

    MainWindow w;

    w.show();

    return a.exec();

}

<RCC>
    <qresource prefix="/images">
        <file alias="file-open">res/file-open.png</file>
        <file alias="file-save">res/file-save.png</file>
    </qresource>
</RCC>