Estou fazendo um modulo flutter em um app android no entanto não estou conseguindo enviar dados para o módulo. Alguém já passou por isso e conseguiu resolver?

gistfile1.txt

import 'package:app_pratico_flutter_module/pages/nova_pagina.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:toast/toast.dart';

void main() {
//  runApp(
//    choseWidget(window.defaultRouteName),
//  );

  runApp(MaterialApp(
    title: "Teste",
    home: HomePage(),
  ));
}

Widget choseWidget(String route) {
  switch (route) {
    case "r1":
      return MyfluterView();
    default:
      return Center(
        child: Text("Unown route"),
      );
  }
}

class MyfluterView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  static const plataform = const MethodChannel('demo.app.flutter.mensagem');
  String _message = "Sem mensagem ainda";

  @override
  void initState() {

    _getMessage().then((String message){
      Toast.show(message ?? "mensagem nula", context, duration: Toast.LENGTH_LONG);
      setState(() {
        _message = message;
        Toast.show(message ??"teste", context);
      });
    });

  }

  Future<String> _getMessage() async {
    String value;
    try {
      value = await plataform.invokeMethod('getMessage');
      Toast.show(value, context);
    } catch(e) {
      print(e);
      Toast.show(e.toString(), context);

    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Card(
        color: Colors.green,
        shape: RoundedRectangleBorder(),
        child: Center(
          child: FlatButton(
              onPressed: () {
                Navigator.push(context,
                    MaterialPageRoute(builder: (context) => MyHomePage()));
              },
              child: Text(_message ?? "Não recebeu mensagem")),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.white,
        onPressed: () {
          _getMessage().then((String message){
            Toast.show(message ?? "mensagem nula", context, duration: Toast.LENGTH_LONG);
            setState(() {
              _message = message;
              Toast.show(message ??"teste", context);
            });
          });
//          Navigator.push(
//              context, MaterialPageRoute(builder: (context) => MyHomePage()));
        },
        child: Icon(Icons.add),
      ),
    );
  }

}



import android.content.Context;
import android.content.ContextWrapper;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.Toast;

import io.flutter.app.FlutterActivity;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.view.FlutterView;
import quadritech.qclass.R;

public class FlutterTestActivity extends FlutterActivity {

    private static final String CHANNEL = "demo.app.flutter.mensagem";
    private View flutterView;
    private FrameLayout.LayoutParams frameLayout;
    private String sharedText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_flutter_test);
        findViewById(R.id.btn_abre_flutter).setOnClickListener(view -> abreFlutter());
//        this.flutterView = Flutter.createView(FlutterTestActivity, this,"r1");
//
//        this.frameLayout = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);

        new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(new MethodChannel.MethodCallHandler() {
            @Override
            public void onMethodCall(@NonNull MethodCall methodCall, @NonNull MethodChannel.Result result) {
                if (methodCall.method.equals("getMessage")) {
                    String mensagem = "Olá vindo do android";
                    result.success(mensagem);
                    Toast.makeText(FlutterTestActivity.this, mensagem, Toast.LENGTH_LONG).show();
                }
            }
        });

    }



    private void abreFlutter() {

        startActivity(new Intent(FlutterTestActivity.this, NovaActivity.class));
        Toast.makeText(this, "Testando botão", Toast.LENGTH_LONG).show();

    }

}