Android -启动视频时暂停音乐播放器

Question

我有一个音频播放器和视频播放器的应用程序。我希望当音频播放器在后台播放而我启动视频时，音频播放器会自动停止播放。

我可以通过广播接收器轻松地实现这一点，方法是在打开视频时发送意图，并在音频播放器中侦听该意图，然后在onReceive()中停止该意图。

但是，我想将此功能不仅扩展到我的音频播放器，而且扩展到所有音频播放器。所以我在想，当视频播放器打开时，是否有发送的标准意图？

Answer 1

为此，您应该使用audio focus。Cf RandomMusicPlayer示例安卓项目：

public class AudioFocusHelper {
    AudioManager mAM;
    MusicFocusable mFocusable;

    private final AudioManager.OnAudioFocusChangeListener listener = new AudioManager.OnAudioFocusChangeListener() {

        @Override
        /** 
         * Called by AudioManager on audio focus changes. We implement this by calling our
         * MusicFocusable appropriately to relay the message.
         */
        public void onAudioFocusChange(int focusChange) {
            if (mFocusable == null) return;
            switch (focusChange) {
                case AudioManager.AUDIOFOCUS_GAIN:
                    mFocusable.onGainedAudioFocus();
                    break;
                case AudioManager.AUDIOFOCUS_LOSS:
                case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
                    mFocusable.onLostAudioFocus(false);
                    break;
                case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
                    mFocusable.onLostAudioFocus(true);
                    break;
                 default:
            }
        }
    };;

    public AudioFocusHelper(Context ctx, MusicFocusable focusable) {
        mAM = (AudioManager) ctx.getSystemService(Context.AUDIO_SERVICE);
        mFocusable = focusable;
    }

    /** Requests audio focus. Returns whether request was successful or not. */
    public boolean requestFocus() {
        return AudioManager.AUDIOFOCUS_REQUEST_GRANTED ==
            mAM.requestAudioFocus(listener, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);
    }

    /** Abandons audio focus. Returns whether request was successful or not. */
    public boolean abandonFocus() {
        return AudioManager.AUDIOFOCUS_REQUEST_GRANTED == mAM.abandonAudioFocus(listener);
    }
}