Audio Focus Series: write a demo to understand audio focus and audiomananger

Let's see the test results first ：

1. To open the first demo, Click on “start” wait a while （ Local audio loading takes time ）, The sound of the car will be played in cycles .
2. home Key back to desktop , Find cool dog music APP And open , Play a song , At this time logcat It will print AUDIOFOCUS_LOSS,Demo App Will pause the play .
3. Manually pause the cool dog music player （log There will be no change , That is, there is no trigger AUDIOFOCUS_GAIN）.
4. set alarm , Alarm clock trigger ,log Show AUDIOFOCUS_LOSS_TRANSIENT
5. Turn off the alarm clock ,log Show AUDIOFOCUS_GAIN

Demo Source code

The layout file is just a button , Write your own layout , complete Demo The code is as follows , The notes are very clear , No explanation .

public class MainActivity extends AppCompatActivity {
    
    private final String TAG = "xxx";

    private AudioManager mAudioManager;
    private MediaPlayer mMediaPlayer;
    private Button btmMusic;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initData();
        initView();
    }

    private void initData() {
    
        // initialization AudioManager object 
        mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
        // Application focus 
        mAudioManager.requestAudioFocus(mAudioFocusChange, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN_TRANSIENT);
        AssetFileDescriptor fileDescriptor;
        try {
    
            // Get audio files 
            fileDescriptor = this.getAssets().openFd("11582.mp3");
            // Instantiation MediaPlayer object 
            mMediaPlayer = new MediaPlayer();
            // Set the playback stream type 
            mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
            // Set the playback source , There are multiple parameters to choose , Refer to relevant documents for details , This article aims to introduce audio focus 
            mMediaPlayer.setDataSource(fileDescriptor.getFileDescriptor(),
                    fileDescriptor.getStartOffset(),
                    fileDescriptor.getLength());
            // Set up looping 
            mMediaPlayer.setLooping(true);
            // Ready to monitor 
            mMediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
    
                @Override
                public void onPrepared(MediaPlayer mp) {
    
                    // Automatically play after preparation 
                    mMediaPlayer.start();
                }
            });
            // Asynchronous preparation 
            mMediaPlayer.prepareAsync();
        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }

    private void initView() {
    
        btmMusic = (Button) findViewById(R.id.btm_music);
        if (btmMusic != null) {
    
            btmMusic.setOnClickListener(new View.OnClickListener() {
    
                @Override
                public void onClick(View v) {
    
                    if (mMediaPlayer != null) {
    
                        if (mMediaPlayer.isPlaying()) {
    
                            stop();
                        } else {
    
                            start();
                        }
                    }
                }
            });
        }
    }


    private void start() {
    
        btmMusic.setText("Stop");
        mAudioManager.requestAudioFocus(mAudioFocusChange, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);
        mMediaPlayer.start();
    }

    private void stop() {
    
        btmMusic.setText("Start");
        mMediaPlayer.pause();

    }

    /** *  Focus change listener  */
    private AudioManager.OnAudioFocusChangeListener mAudioFocusChange = new AudioManager.OnAudioFocusChangeListener() {
    
        @Override
        public void onAudioFocusChange(int focusChange) {
    
            switch (focusChange) {
    
                case AudioManager.AUDIOFOCUS_LOSS:
                    // Lost focus for a long time 
                    Log.d(TAG, "AUDIOFOCUS_LOSS");
                    stop();
                    // Release focus 
                    mAudioManager.abandonAudioFocus(mAudioFocusChange);
                    break;
                case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
                    // Temporary loss of focus 
                    stop();
                    Log.d(TAG, "AUDIOFOCUS_LOSS_TRANSIENT");
                    break;
                case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
                    // Temporarily lose focus and reduce sound 
                    Log.d(TAG, "AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK");
                    break;
                case AudioManager.AUDIOFOCUS_GAIN:
                    // Regain focus 
                    Log.d(TAG, "AUDIOFOCUS_GAIN");
                    start();
                    break;
            }
        }
    };

    @Override
    protected void onDestroy() {
    
        super.onDestroy();
        mMediaPlayer.release();
        mAudioManager.abandonAudioFocus(mAudioFocusChange);
    }
}

What are the practical scenarios of audio focus ？

• Turn on cool dog music and play a song , And on again B standing , Play the video , At this time, cool dog will automatically pause , Press the back key to exit the video playback , Cool dog will automatically resume playing music .

How does the official website describe the audio focus ？

Audio focus improvement
AudioManager.requestAudioFocus()