如何在Flutter中嵌套Android布局

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Expanded(
            child: Center(
              child: Text(
                'Android按钮点击了 $_counter 次',
                style: const TextStyle(fontSize: 17.0)),
            ),
          ),
          Container(
            padding: const EdgeInsets.only(bottom: 15.0, left: 5.0),
            child: Row(
              children: <Widget>[
                Image.asset('assets/flutter-mark-square-64.png', scale: 1.5),
                const Text('Flutter', style: TextStyle(fontSize: 30.0)),
              ],
            ),
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _sendFlutterIncrement,
        child: const Icon(Icons.add),
      ),
    );
  }

  <io.flutter.embedding.android.FlutterView
    android:id="@ id/flutter_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight="1"
    />

  <androidx.coordinatorlayout.widget.CoordinatorLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight="1"
    android:background="@color/grey"
    >

    <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical"
      >

      <TextView
        android:id="@ id/button_tap"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/button_tap"
        ...
        />

      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/android"
        ...
        />

    </LinearLayout>

    <com.google.android.material.floatingactionbutton.FloatingActionButton
      android:id="@ id/button"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
       ...
      />

  </androidx.coordinatorlayout.widget.CoordinatorLayout>

  static const String _channel = 'increment';
  static const String _pong = 'pong';
  static const String _emptyMessage = '';
  static const BasicMessageChannel<String> platform =
      BasicMessageChannel<String>(_channel, StringCodec());
  int _counter = 0;
  
  @override
  void initState() {
    super.initState();
    platform.setMessageHandler(_handlePlatformIncrement);
  }
  
 Future<String> _handlePlatformIncrement(String message) async {
    setState(() {
      _counter  ;
    });
    return _emptyMessage;
  }

  void _sendFlutterIncrement() {
    platform.send(_pong);
  }

    private static FlutterEngine flutterEngine;
    private FlutterView flutterView;
    private int counter;
    private static final String CHANNEL = "increment";
    private static final String EMPTY_MESSAGE = "";
    private static final String PING = "ping";
    private BasicMessageChannel<String> messageChannel;
    ...
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
            if (flutterEngine == null) {
            flutterEngine = new FlutterEngine(this, args);
            flutterEngine.getDartExecutor().executeDartEntrypoint(
                DartEntrypoint.createDefault()
            );
        }
        ...
        flutterView = findViewById(R.id.flutter_view);
        flutterView.attachToFlutterEngine(flutterEngine);

        messageChannel = new BasicMessageChannel<>(flutterEngine.getDartExecutor(), CHANNEL, StringCodec.INSTANCE);
        messageChannel.
            setMessageHandler(new MessageHandler<String>() {
                @Override
                public void onMessage(String s, Reply<String> reply) {
                    onFlutterIncrement();
                    reply.reply(EMPTY_MESSAGE);
                }
            });

        FloatingActionButton fab = findViewById(R.id.button);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                sendAndroidIncrement();
            }
        });
        ...

    private void sendAndroidIncrement() {
        messageChannel.send(PING);
    }

  @Override
    protected void onResume() {
        super.onResume();
        flutterEngine.getLifecycleChannel().appIsResumed();
    }

    @Override
    protected void onPause() {
        super.onPause();
        flutterEngine.getLifecycleChannel().appIsInactive();
    }

    @Override
    protected void onStop() {
        super.onStop();
        flutterEngine.getLifecycleChannel().appIsPaused();
    }

    @Override
    protected void onDestroy() {
        flutterView.detachFromFlutterEngine();
        super.onDestroy();
    }