1.  修改右键菜单策略

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    addAction(new QAction("新增",this));
    addAction(new QAction("删除",this));

    setContextMenuPolicy(Qt::ActionsContextMenu);
}

构造函数中直接用addAction添加了两个菜单项，setContextMenuPolicy(Qt::ActionsContextMenu)这一句是启动右键菜单策略，然后运行右击就会有菜单弹出。运行如下。

2. 重写mousePressEvent()方法。

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    m_contextMenu = new QMenu;  //这是右击弹出的菜单
    m_addAction = new QAction("新增",this);
    m_delAction = new QAction("删除",this);
    //给菜单添加菜单项
    m_contextMenu->addAction(m_addAction);
    m_contextMenu->addAction(m_delAction);
}

void MainWindow::mousePressEvent(QMouseEvent *event)
{
    //确保右键点击，然后跳出菜单.
    if (event->button() == Qt::RightButton)
    {
        //在鼠标右击的地方弹出菜单
        m_contextMenu->exec(event->globalPos());
    }

    event->accept();
}

3. 重写contextMenuEvent()

同2，只需要把mousePressEvent()换成contextMenuEvent()；具体代码如下。

void MainWindow::contextMenuEvent(QContextMenuEvent *event)
{
    //让菜单移动到鼠标位置并显示.
    m_contextMenu->exec(event->globalPos());
}