管理媒体播放（2）管理媒体的聚焦

最新推荐文章于 2025-02-04 11:00:00 发布

原创最新推荐文章于 2025-02-04 11:00:00 发布 · 279 阅读

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文章标签：

#audio #多媒体

请求获得焦点

在我们的app开始播放媒体之前，它应该为有要被播放的媒体流保留焦点。调用requestAudioFocus() 方法，如果我们请求成功的话，会返回AUDIOFOCUS_REQUEST_GRANTED。

AudioManager am = mContext.getSystemService(Context.AUDIO_SERVICE);
...

// Request audio focus for playback
int result = am.requestAudioFocus(afChangeListener,
                                 // Use the music stream.
                                 AudioManager.STREAM_MUSIC,
                                 // Request permanent focus.
                                 AudioManager.AUDIOFOCUS_GAIN);
   
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
    am.unregisterMediaButtonEventReceiver(RemoteControlReceiver);
    // Start playback.
}

// Abandon audio focus when playback complete    
am.abandonAudioFocus(afChangeListener);

// Request audio focus for playback
int result = am.requestAudioFocus(afChangeListener,
                             // Use the music stream.
                             AudioManager.STREAM_MUSIC,
                             // Request permanent focus.
                             AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK);
   
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
    // Start playback.
}

处理失去焦点

OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {
    public void onAudioFocusChange(int focusChange) {
        if (focusChange == AUDIOFOCUS_LOSS_TRANSIENT
            // Pause playback
        } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) {
            // Resume playback 
        } else if (focusChange == AudioManager.AUDIOFOCUS_LOSS) {
            am.unregisterMediaButtonEventReceiver(RemoteControlReceiver);
            am.abandonAudioFocus(afChangeListener);
            // Stop playback
        }
    }
};

OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {
    public void onAudioFocusChange(int focusChange) {
        if (focusChange == AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK) {
            // Lower the volume
        } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) {
            // Raise it back to normal
        }
    }
};