问Flutter:尝试在FlutterEngine中自动注册插件，但未能找到并调用GeneratedPluginRegistrant

EN

package your.package.name

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

private static void registerPlugins(@NonNull FlutterEngine flutterEngine) {
  try {
    Class<?> generatedPluginRegistrant =
        Class.forName("io.flutter.plugins.GeneratedPluginRegistrant");
    Method registrationMethod =
        generatedPluginRegistrant.getDeclaredMethod("registerWith", 
FlutterEngine.class);
    registrationMethod.invoke(null, flutterEngine);
  } catch (Exception e) {
    Log.w(
        TAG,
        "Tried to automatically register plugins with FlutterEngine ("
            + flutterEngine
            + ") but could not find and invoke the GeneratedPluginRegistrant.");
  }
}

public class MyPlugin implements FlutterPlugin, ActivityAware {
    private MethodChannel methodChannel;
    private CustomMethodHandler methodHandler;
    private ActivityPluginBinding mActivityBinding;

    private void initChannels(final BinaryMessenger messenger) {
        methodChannel = new MethodChannel(messenger, Channel.MY_METHOD_CHANNEL);
        methodHandler= new CustomMethodHandler(null);
        methodChannel.setMethodCallHandler(authMethodHandler);
    }

    private void teardownChannels() {
        methodChannel.setMethodCallHandler(null);
        methodChannel = null;
    }

    private void setupActivity(Activity activity) {
        methodChannel.setActivity(activity);
    }

    private void teardownActivity() {
        methodChannel.setActivity(null);
    }

    @Override
    public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
        // Debug here for errors.
        initChannels(flutterPluginBinding.getBinaryMessenger());
    }

    public static void registerWith(Registrar registrar) {
        MyPlugin myPlugin = new MyPlugin();
        myPlugin.initChannels(registrar.messenger());
        myPlugin.setupActivity(registrar.activity());
    }

    @Override
    public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
        teardownChannels();
    }

    @Override
    public void onAttachedToActivity(@NonNull ActivityPluginBinding binding) {
        // Debug here for errors.
        mActivityBinding = binding;
        setupActivity(mActivityBinding.getActivity());
    }

    @Override
    public void onDetachedFromActivityForConfigChanges() {
        teardownActivity();
    }

    @Override
    public void onReattachedToActivityForConfigChanges(@NonNull ActivityPluginBinding binding) {
        mActivityBinding = binding;
        setupActivity(mActivityBinding.getActivity());
    }

    @Override
    public void onDetachedFromActivity() {
        teardownActivity();
    }

}

package com.example.appname;
import io.flutter.app.FlutterApplication;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
import io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin;
import io.flutter.plugins.firebasemessaging.FlutterFirebaseMessagingService;
import com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin;

public class Application extends FlutterApplication implements PluginRegistrantCallback {
  @Override
  public void onCreate() {
    super.onCreate();
    FlutterFirebaseMessagingService.setPluginRegistrant(this);
  }

  @Override
  public void registerWith(PluginRegistry registry) {
    FirebaseCloudMessagingPluginRegistrant.registerWith(registry);
  }
}

package com.example.appname;

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugins.GeneratedPluginRegistrant;

public class MainActivity extends FlutterActivity {
 @Override
 public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
   GeneratedPluginRegistrant.registerWith(flutterEngine);
 }
}

package com.example.appname;
import com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin;

public final class FirebaseCloudMessagingPluginRegistrant{
  public static void registerWith(PluginRegistry registry) {
    if (alreadyRegisteredWith(registry)) {
      return;
    }
    FirebaseMessagingPlugin.registerWith(registry.registrarFor("io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin"));
    FlutterLocalNotificationsPlugin.registerWith(registry.registrarFor("com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin"));
  }

  private static boolean alreadyRegisteredWith(PluginRegistry registry) {
    final String key = FirebaseCloudMessagingPluginRegistrant.class.getCanonicalName();
    if (registry.hasPlugin(key)) {
      return true;
    }
    registry.registrarFor(key);
    return false;
  }
}

<application android:name=".Application"
<activity android:name=".MainActivity"