MediaSession.SessionCallback

public int onCommandRequest(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller,
    @NonNull SessionCommand command
)

Called when a controller sent a command which will be sent directly to one of the following:

• SessionPlayer
• android.media.AudioManager

Return RESULT_SUCCESS to proceed the command. If something else is returned, command wouldn't be sent and the controller would receive the code with it.

public @Nullable SessionCommandGroup onConnect(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called when a controller is created for this session. Return allowed commands for controller. By default it allows all connection requests and commands.

You can reject the connection by return null. In that case, the controller receives onDisconnected and cannot be used.

The controller hasn't connected yet in this method, so calls to the controller (e.g. sendCustomCommand, setCustomLayout) would be ignored. Override onPostConnect for the custom initialization for the controller instead.

public @Nullable MediaItem onCreateMediaItem(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller,
    @NonNull String mediaId
)

Called when a controller has sent a command with a MediaItem to add a new media item to this session. Being specific, this will be called for following APIs.

1. addPlaylistItem
2. replacePlaylistItem
3. setPlaylist
4. setMediaItem

If the given media ID is valid, you should return the media item with the given media ID. If the ID doesn't match, an RuntimeException will be thrown. You may return null if the given item is invalid. Here's the behavior when it happens.

This will be called on the same thread where onCommandRequest and commands with the media controller will be executed.

Default implementation returns the null.

public @NonNull SessionResult onCustomCommand(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller,
    @NonNull SessionCommand customCommand,
    @Nullable Bundle args
)

Called when a controller sent a custom command through sendCustomCommand.

Interoperability: This would be also called by #sendCustomAction(String, Bundle, CustomActionCallback). If so, extra from sendCustomAction will be considered as args and customCommand would have null extra.

public void onDisconnected(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called when a controller is disconnected.

Interoperability: For legacy controller, this is called when the controller doesn't send any command for a while. It's because there were no explicit disconnect API in legacy controller API.

public int onFastForward(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called when a controller called fastForward.

It can be implemented in many ways. For example, it can be implemented by seeking forward once, series of seeking forward, or increasing playback speed.

public void onPostConnect(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called immediately after a controller is connected. This is a convenient method to add custom initialization between the session and a controller.

Note that calls to the controller (e.g. sendCustomCommand, setCustomLayout) work here but don't work in onConnect because the controller hasn't connected yet in onConnect.

public int onRewind(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called when a controller called rewind.

It can be implemented in many ways. For example, it can be implemented by seeking backward once, series of seeking backward, or decreasing playback speed.

public int onSetMediaUri(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller,
    @NonNull Uri uri,
    @Nullable Bundle extras
)

Called when a controller requested to set the specific media item(s) represented by a URI through setMediaUri.

The implementation should create proper media item(s) for the given uri and call setMediaItem or setPlaylist.

When MediaControllerCompat is connected and sends commands with following methods, the uri would have the following patterns:

prepare or play would be followed if this is called by above methods.

public int onSetRating(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller,
    @NonNull String mediaId,
    @NonNull Rating rating
)

Called when a controller set rating of a media item through setRating.

To allow setting user rating for a MediaItem, the media item's metadata should have Rating with the key METADATA_KEY_USER_RATING, in order to provide possible rating style for controller. Controller will follow the rating style.

public int onSkipBackward(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called when a controller called skipBackward.

It's recommended to seek backward within the current media item, but its detail may vary. For example, it can be implemented by seeking backward for the fixed amount of seconds, or seeking backward to the nearest bookmark.

public int onSkipForward(
    @NonNull MediaSession session,
    @NonNull MediaSession.ControllerInfo controller
)

Called when a controller called skipForward.

It's recommended to seek forward within the current media item, but its detail may vary. For example, it can be implemented by seeking forward for the fixed amount of seconds, or seeking forward to the nearest bookmark.