Experimental: Create Flutter Plugin

Quick Migration Steps

These instructions are for the ecosystem team as they implement parallel plugin support for the new embedding.

1. Create a new [MyPlugin].java file at dev.flutter.plugins.[myplugin].

2. Have [MyPlugin] implement FlutterPlugin.

3. (Optional) If your plugin needs an Activity reference, also implement ActivityAware.

4. (Optional) If your plugin is expected to be held in a background Service at any point in time, implement ServiceAware.

5. Implement each plugin method as desired. Set up references as you attach to things. Clean up references as you detach from things.

6. Consider separating the MethodChannelHandler from the old version of [MyPlugin] and then use that MethodChannelHandler in both io.flutter.plugins.[myplugin].[MyPlugin].java and dev.flutter.plugins.[myplugin].[MyPlugin].java.

7. Add a static registerWith() method to your new [MyPlugin] class and have it call through to the registerWith() method in your old [MyPlugin] class.

8. (Optional but Recommended) Add unit tests to validate the serialization/deserialization of all incoming/outgoing channel messages.

Basic Plugin

To get started with a Flutter Android plugin in code, start by implementing FlutterPlugin.

public class MyPlugin implements FlutterPlugin {
  @Override
  public void onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
    // TODO: your plugin is now attached to a Flutter experience.
  }

  @Override
  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
    // TODO: your plugin is no longer attached to a Flutter experience.
  }
}

As shown above, your plugin may or may not be associated with a given Flutter experience at any given moment in time. You should take care to initialize your plugin's behavior in onAttachedToEngine(), and then cleanup your plugin's references in onDetachedFromEngine().

The FlutterPluginBinding provides your plugin with a few important references:

• binding.getFlutterEngine(): Returns the FlutterEngine that your plugin is attached to, providing access to components like the DartExecutor, FlutterRenderer, and more.
• binding.getApplicationContext(): Returns the Android application's Context for the running app.
• binding.getLifecycle(): Returns a reference that can be used to obtain a Lifecycle object. If you need to use this lifecycle reference then you need add a project dependency on Flutter's Android lifecycle package.

UI/Activity Plugin

If your plugin needs to interact with the UI, such as requesting permissions, or altering Android UI chrome, then you need to take additional steps to define your plugin. You must implement the ActivityAware interface.

public class MyPlugin implements FlutterPlugin, ActivityAware {
  //...normal plugin behavior is hidden...

  @Override
  public void onAttachedToActivity(ActivityPluginBinding activityPluginBinding) {
    // TODO: your plugin is now attached to an Activity
  }

  @Override
  public void onDetachedFromActivityForConfigChanges() {
    // TODO: the Activity your plugin was attached to was destroyed to change configuration.
    // This call will be followed by onReattachedToActivityForConfigChanges().
  }

  @Override
  public void onReattachedToActivityForConfigChanges(ActivityPluginBinding activityPluginBinding) {
    // TODO: your plugin is now attached to a new Activity after a configuration change.
  }

  @Override
  public void onDetachedFromActivity() {
    // TODO: your plugin is no longer associated with an Activity. Clean up references.
  }
}

To interact with an Activity, your ActivityAware plugin must implement appropriate behavior at 4 stages. First, your plugin is attached to an Activity. You can access that Activity and a number of its callbacks through the provided ActivityPluginBinding.

Since Activitys can be destroyed during configuration changes, you must cleanup any references to the given Activity in onDetachedFromActivityForConfigChanges(), and then re-establish those references in onReattachedToActivityForConfigChanges().

Finally, in onDetachedFromActivity() your plugin should clean up all references related to Activity behavior and return to a non-UI configuration.

Service Plugin

TODO

ContentProvider Plugin

TODO