使用QT创建一个界面，可以通过按键实现按1 音乐暂停 按 2 音乐播放 按 3 单曲循环 按 4 列表循环 按 5 随机播放 按 6 上一首歌 按 7 下一首歌 按 0 退出播放器等功能，生成代码

以下是一个使用QT实现的简单音乐播放器界面的代码，包括上述功能：

#include <QMainWindow>
#include <QMediaPlayer>
#include <QMediaPlaylist>
#include <QFileDialog>
#include <QMessageBox>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_actionOpen_triggered();
    void on_btnPlayPause_clicked();
    void on_btnStop_clicked();
    void on_btnPrev_clicked();
    void on_btnNext_clicked();
    void on_btnLoop_clicked();
    void on_btnShuffle_clicked();
    void on_player_stateChanged(QMediaPlayer::State state);
    void on_player_error(QMediaPlayer::Error error);

private:
    Ui::MainWindow *ui;
    QMediaPlayer *player;
    QMediaPlaylist *playlist;
    bool isPlaying;
};

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow),
    player(new QMediaPlayer(this)),
    playlist(new QMediaPlaylist(this)),
    isPlaying(false)
{
    ui->setupUi(this);

    // Connect signals and slots
    connect(player, SIGNAL(stateChanged(QMediaPlayer::State)), this, SLOT(on_player_stateChanged(QMediaPlayer::State)));
    connect(player, SIGNAL(error(QMediaPlayer::Error)), this, SLOT(on_player_error(QMediaPlayer::Error)));

    // Set up playlist
    playlist->setPlaybackMode(QMediaPlaylist::Sequential);
    player->setPlaylist(playlist);

    // Set up buttons
    ui->btnPlayPause->setIcon(QIcon(":/icons/play.svg"));
    ui->btnStop->setIcon(QIcon(":/icons/stop.svg"));
    ui->btnLoop->setIcon(QIcon(":/icons/loop.svg"));
    ui->btnShuffle->setIcon(QIcon(":/icons/shuffle.svg"));
}

MainWindow::~MainWindow()
{
    delete ui;
    delete player;
    delete playlist;
}

void MainWindow::on_actionOpen_triggered()
{
    QStringList fileNames = QFileDialog::getOpenFileNames(this, tr("Open Files"), "", tr("Audio Files (*.mp3 *.wav)"));
    if (fileNames.isEmpty()) {
        return;
    }

    // Add files to playlist
    foreach (QString fileName, fileNames) {
        playlist->addMedia(QUrl::fromLocalFile(fileName));
    }

    // Start playing if not already playing
    if (!isPlaying) {
        player->play();
        ui->btnPlayPause->setIcon(QIcon(":/icons/pause.svg"));
        isPlaying = true;
    }
}

void MainWindow::on_btnPlayPause_clicked()
{
    if (player->state() == QMediaPlayer::PlayingState) {
        player->pause();
        ui->btnPlayPause->setIcon(QIcon(":/icons/play.svg"));
        isPlaying = false;
    } else {
        player->play();
        ui->btnPlayPause->setIcon(QIcon(":/icons/pause.svg"));
        isPlaying = true;
    }
}

void MainWindow::on_btnStop_clicked()
{
    player->stop();
    ui->btnPlayPause->setIcon(QIcon(":/icons/play.svg"));
    isPlaying = false;
}

void MainWindow::on_btnPrev_clicked()
{
    playlist->previous();
}

void MainWindow::on_btnNext_clicked()
{
    playlist->next();
}

void MainWindow::on_btnLoop_clicked()
{
    QMediaPlaylist::PlaybackMode mode = playlist->playbackMode();
    if (mode == QMediaPlaylist::Sequential) {
        playlist->setPlaybackMode(QMediaPlaylist::CurrentItemInLoop);
        ui->btnLoop->setIcon(QIcon(":/icons/loop-one.svg"));
    } else {
        playlist->setPlaybackMode(QMediaPlaylist::Sequential);
        ui->btnLoop->setIcon(QIcon(":/icons/loop.svg"));
    }
}

void MainWindow::on_btnShuffle_clicked()
{
    playlist->setPlaybackMode(QMediaPlaylist::Random);
}

void MainWindow::on_player_stateChanged(QMediaPlayer::State state)
{
    if (state == QMediaPlayer::StoppedState) {
        ui->btnPlayPause->setIcon(QIcon(":/icons/play.svg"));
        isPlaying = false;
    }
}

void MainWindow::on_player_error(QMediaPlayer::Error error)
{
    QMessageBox::critical(this, tr("Error"), player->errorString());
}

界面设计可以通过QT Designer进行，然后使用uic工具将.ui文件转换为对应的C++代码。