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点击play按钮播放或暂停音乐，拖动进度条，音乐对应播放。

	QWidget window;

	QPushButton* playButton = new QPushButton("Play");

	// Qt 播放音乐
	// 创建 QMediaPlayer 对象
	QMediaPlayer* player = new QMediaPlayer;

	// 指定音频文件的路径
	QString audioFilePath = QString::fromLocal8Bit(std::string("./红昭愿.mp3").c_str());

	// 加载音频文件
	player->setMedia(QUrl::fromLocalFile(audioFilePath));

	// 创建进度条
	QSlider* seekSlider = new QSlider(Qt::Horizontal);
	QObject::connect(seekSlider, &QSlider::sliderMoved, [&](int position) {

		if (seekSlider->isSliderDown())
			player->setPosition(position * 1000);
	});

	// 音频准备就绪后，获取音频的总时长(ms)
	QObject::connect(player, &QMediaPlayer::mediaStatusChanged, [=](QMediaPlayer::MediaStatus status) {
		if (status == QMediaPlayer::BufferedMedia) {
			qint64 duration = player->duration();
			qDebug() << duration;
			return;
		}
	});

	QObject::connect(playButton, &QPushButton::clicked, [=]() 
	{
		if (player->state() == QMediaPlayer::PlayingState)
			player->pause();
		else
			player->play();
	});

	QVBoxLayout* layout = new QVBoxLayout;
	layout->addWidget(playButton);
	layout->addWidget(seekSlider);
	window.setLayout(layout);

	window.setWindowTitle("QtPlayMusic");

	window.show();