QAction、QMenu、QToolbar

    QAction* openAction =  new QAction("打开",this);
    openAction->setStatusTip("open file");
    openAction->connect(openAction,&QAction::triggered,[](){qDebug()<<"openAction";});

    QAction* closeAction =  new QAction("关闭",this);
    closeAction->setStatusTip("close file");
    closeAction->connect(closeAction,&QAction::triggered,[](){qDebug()<<"closeAction";});

    QMenu* filemenu = new QMenu("文件",this);
    filemenu->addAction(openAction);
    filemenu->addAction(closeAction);

    menuBar()->addMenu(filemenu);

    QToolBar* opentoolbar = new QToolBar("open toolbar",this);
    opentoolbar->addAction(openAction);
    addToolBar(opentoolbar);

    QToolBar* closetoolbar = new QToolBar("close tool bar",this);
    closetoolbar->addAction(closeAction);
    addToolBar(closetoolbar);