Os callbacks de sessão de mídia chamam métodos em várias APIs para controlar o player, gerenciar a seleção de áudio,
e se comunicar com a sessão de mídia e o serviço de navegador de mídia. Observe que o
A lógica MediaSession que responde a callbacks precisa ser consistente. O comportamento
da chamada de retorno não pode depender da identidade do autor da chamada, que pode ser
uma atividade no mesmo app executando a MediaSession ou qualquer outro app com uma
O dispositivo MediaController se conectou a MediaSession.
A tabela a seguir resume como essas tarefas são distribuídas entre os callbacks.
| onPlay() | onPause() | onStop() | |
| Seleção de áudio | requestFocus() transmitindo a OnAudioFocusChangeListener.Sempre chame requestFocus() primeiro e continue somente se o foco for concedido.
|
abandonAudioFocus()
|
|
| Serviço | startService()
|
stopSelf()
|
|
| Sessão de mídia | setActive(true)
- Atualizar metadados e estado |
- Atualizar metadados e estado | setActive(false)
- Atualizar metadados e estado |
| Implementação do player | Iniciar o player | Pausar o player | Parar o player |
| Ficar barulhento | Registre seu BroadcastReceiver
|
Cancelar o registro do seu BroadcastReceiver
|
|
| Notificações | startForeground(notification)
|
stopForeground(false)
|
stopForeground(false)
|
Veja um exemplo de framework para o callback:
private val intentFilter = IntentFilter(ACTION_AUDIO_BECOMING_NOISY)
// Defined elsewhere...
private lateinit var afChangeListener: AudioManager.OnAudioFocusChangeListener
private val myNoisyAudioStreamReceiver = BecomingNoisyReceiver()
private lateinit var myPlayerNotification: MediaStyleNotification
private lateinit var mediaSession: MediaSessionCompat
private lateinit var service: MediaBrowserService
private lateinit var player: SomeKindOfPlayer
private lateinit var audioFocusRequest: AudioFocusRequest
private val callback = object: MediaSessionCompat.Callback() {
override fun onPlay() {
val am = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
// Request audio focus for playback, this registers the afChangeListener
audioFocusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN).run {
setOnAudioFocusChangeListener(afChangeListener)
setAudioAttributes(AudioAttributes.Builder().run {
setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
build()
})
build()
}
val result = am.requestAudioFocus(audioFocusRequest)
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
// Start the service
startService(Intent(context, MediaBrowserService::class.java))
// Set the session active (and update metadata and state)
mediaSession.isActive = true
// start the player (custom call)
player.start()
// Register BECOME_NOISY BroadcastReceiver
registerReceiver(myNoisyAudioStreamReceiver, intentFilter)
// Put the service in the foreground, post notification
service.startForeground(id, myPlayerNotification)
}
}
public override fun onStop() {
val am = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
// Abandon audio focus
am.abandonAudioFocusRequest(audioFocusRequest)
unregisterReceiver(myNoisyAudioStreamReceiver)
// Stop the service
service.stopSelf()
// Set the session inactive (and update metadata and state)
mediaSession.isActive = false
// stop the player (custom call)
player.stop()
// Take the service out of the foreground
service.stopForeground(false)
}
public override fun onPause() {
val am = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
// Update metadata and state
// pause the player (custom call)
player.pause()
// unregister BECOME_NOISY BroadcastReceiver
unregisterReceiver(myNoisyAudioStreamReceiver)
// Take the service out of the foreground, retain the notification
service.stopForeground(false)
}
}
private IntentFilter intentFilter = new IntentFilter(AudioManager.ACTION_AUDIO_BECOMING_NOISY);
// Defined elsewhere...
private AudioManager.OnAudioFocusChangeListener afChangeListener;
private BecomingNoisyReceiver myNoisyAudioStreamReceiver = new BecomingNoisyReceiver();
private MediaStyleNotification myPlayerNotification;
private MediaSessionCompat mediaSession;
private MediaBrowserService service;
private SomeKindOfPlayer player;
private AudioFocusRequest audioFocusRequest;
MediaSessionCompat.Callback callback = new
MediaSessionCompat.Callback() {
@Override
public void onPlay() {
AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
// Request audio focus for playback, this registers the afChangeListener
AudioAttributes attrs = new AudioAttributes.Builder()
.setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
.build();
audioFocusRequest = new AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN)
.setOnAudioFocusChangeListener(afChangeListener)
.setAudioAttributes(attrs)
.build();
int result = am.requestAudioFocus(audioFocusRequest);
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
// Start the service
startService(new Intent(context, MediaBrowserService.class));
// Set the session active (and update metadata and state)
mediaSession.setActive(true);
// start the player (custom call)
player.start();
// Register BECOME_NOISY BroadcastReceiver
registerReceiver(myNoisyAudioStreamReceiver, intentFilter);
// Put the service in the foreground, post notification
service.startForeground(id, myPlayerNotification);
}
}
@Override
public void onStop() {
AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
// Abandon audio focus
am.abandonAudioFocusRequest(audioFocusRequest);
unregisterReceiver(myNoisyAudioStreamReceiver);
// Stop the service
service.stopSelf();
// Set the session inactive (and update metadata and state)
mediaSession.setActive(false);
// stop the player (custom call)
player.stop();
// Take the service out of the foreground
service.stopForeground(false);
}
@Override
public void onPause() {
AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
// Update metadata and state
// pause the player (custom call)
player.pause();
// unregister BECOME_NOISY BroadcastReceiver
unregisterReceiver(myNoisyAudioStreamReceiver);
// Take the service out of the foreground, retain the notification
service.stopForeground(false);
}
};