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

    //设置界面颜色样式
    this->setStyleSheet("background-color:rgb(54,54,54)");

    //创建文件菜单
    QMenu *fileMenuItems = new QMenu;

    //菜单添加icon
    fileMenuItems->setIcon(QIcon(":/resources/file.png"));
    fileMenuItems->setTitle(u8"文件");
    fileMenuItems->setStyleSheet(QString::fromStdString(menuItemQss));

    //为文件菜单添加项目
    QList<QAction*> acList;
    //具体项目
    // action添加icon
    QAction *openFileAc = new QAction(QIcon(":/resources/file.png"), u8"打开文件", this);
    //openFileAc->setShortcuts(QKeySequence::Print);       //设置快捷键
    openFileAc->setShortcut(QKeySequence("Ctrl+8"));  //随意指定快捷键
    QAction *openFloderAc = new QAction(u8"打开文件夹", this);
    QAction *openUrlAc = new QAction(u8"打开url", this);
    //添加菜单项
    acList << openFileAc << openFloderAc << openUrlAc;
    fileMenuItems->addActions(acList);

    
    
    QMenu *pMenu = new QMenu;  //主菜单
    pMenu->addMenu(fileMenuItems);//将文件菜单这个子菜单添加进主菜单
    //为主菜单添加项目
    QAction *play = new QAction(QIcon(":/resources/play.png"), u8"播放", this);
    QAction *tools = new QAction(QIcon(":/resources/tools.png"), u8"工具", this);
    pMenu->addAction(play);
    pMenu->addAction(tools);

    pMenu->addSeparator();
    
    
    //与文件菜单同级别的设置菜单
    QMenu *setMenuItems = new QMenu;
    setMenuItems->setTitle(u8"设置");
    setMenuItems->setIcon(QIcon(":/resources/set.png"));
    //为设置菜单添加项目
    QList<QAction*> setList;
    QAction *sysSetAc = new QAction(u8"系统设置", this);
    QAction *playSetAc = new QAction(u8"播放设置", this);
    QAction *zimuSetAc = new QAction(u8"字幕设置", this);
    setList << sysSetAc << playSetAc << zimuSetAc;
    setMenuItems->addActions(setList);
    setMenuItems->setStyleSheet(QString::fromStdString(menuItemQss));
    pMenu->addMenu(setMenuItems);

    pMenu->addSeparator();

    QAction *exitAc = new QAction(QIcon(":/resources/exit.png"), u8"退出", this);
    pMenu->addAction(exitAc);

    ui->pushButton->setMenu(pMenu);

    connect(openFileAc, &QAction::triggered, [=]{
        QString fileName = QFileDialog::getOpenFileName(this,
                                                        u8"请选择视频文件",
                                                        "D:/",
                                                        "视频(*.mp4 *.flv);;");

        if(fileName.isEmpty())
        {
            return;
        }
    });

    ui->pushButton->setText(u8"QW影音");
    ui->pushButton->setFixedSize(100, 32);
    ui->pushButton->setStyleSheet(QString::fromStdString(button_qss));
    pMenu->setStyleSheet(QString::fromStdString(menuQss));
}

qss.h:

#ifndef QSS_H
#define QSS_H

#include <string>

using namespace std;

string button_qss = R"(
    QPushButton
    {
        font:18px "Microsoft YaHei";
        color:rgb(255,255,255);
        border:none
    }

    QPushButton::menu-indicator:open
    {
        image:url(:/resources/down_arrow.svg);
        subcontrol-position:right center;
        subcontrol-origin:padding;border:none;
    }

    QPushButton::menu-indicator:closed
    {
        image:url(:/resources/up_arrow.svg);
        subcontrol-position:right center;
        subcontrol-origin:padding;border:none;
    }
)";

string menuQss = R"(
    QMenu
    {
        background-color:rgb(53, 63, 73);
    }

    QMenu::item
    {
         font:16px;
         color:white;
         background-color:rgb(53, 63, 73);
         padding:8px 32px;
         margin:8px 8px;
         /*border-bottom:1px solid #DBDBDB;  item底部颜色*/
    }

    /*选择项设置*/
    QMenu::item:selected
    {
         background-color:rgb(54, 54, 54);
    }
)";

string menuItemQss = R"(
    QMenu
    {
        background-color:rgb(73, 73, 73);
    }

    QMenu::item
    {
         font:16px;
         color:white;
         background-color:rgb(73, 73, 73);
         padding:8px 32px;
         margin:8px 8px;
         /*border-bottom:1px solid #DBDBDB;  item底部颜色*/
    }

    /*选择项设置*/
    QMenu::item:selected
    {
         background-color:rgb(54, 54, 54);
    }
)";

#endif // QSS_H