flutter和安卓通信(官方代码)

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() {
  runApp(FlutterView());
}

class FlutterView extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter View',
      theme: ThemeData(
        primarySwatch: Colors.grey,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  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);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Expanded(
            child: Center(
              child: Text(
                'Platform button tapped $_counter time${ _counter == 1 ? '' : 's' }.',
                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),
      ),
    );
  }
}

name: flutter_view
description: A new flutter project.

environment:
  # The pub client defaults to an <2.0.0 sdk constraint which we need to explicitly overwrite.
  sdk: ">=2.0.0-dev.68.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

  characters: 1.1.0-nullsafety.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  collection: 1.15.0-nullsafety.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  meta: 1.3.0-nullsafety.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  typed_data: 1.3.0-nullsafety.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  vector_math: 2.1.0-nullsafety.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"

flutter:
  uses-material-design: true
  assets:
    - assets/flutter-mark-square-64.png

# PUBSPEC CHECKSUM: e9aa

public class MainActivity extends AppCompatActivity {
    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;

    private String[] getArgsFromIntent(Intent intent) {
        // Before adding more entries to this list, consider that arbitrary
        // Android applications can generate intents with extra data and that
        // there are many security-sensitive args in the binary.
        ArrayList<String> args = new ArrayList<>();
        if (intent.getBooleanExtra("trace-startup", false)) {
            args.add("--trace-startup");
        }
        if (intent.getBooleanExtra("start-paused", false)) {
            args.add("--start-paused");
        }
        if (intent.getBooleanExtra("enable-dart-profiling", false)) {
            args.add("--enable-dart-profiling");
        }
        if (!args.isEmpty()) {
            String[] argsArray = new String[args.size()];
            return args.toArray(argsArray);
        }
        return null;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        String[] args = getArgsFromIntent(getIntent());
        if (flutterEngine == null) {
            flutterEngine = new FlutterEngine(this, args);
            flutterEngine.getDartExecutor().executeDartEntrypoint(
                DartEntrypoint.createDefault()
            );
        }
        setContentView(R.layout.flutter_view_layout);
        ActionBar supportActionBar = getSupportActionBar();
        if (supportActionBar != null) {
            supportActionBar.hide();
        }

        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);
    }

    private void onFlutterIncrement() {
        counter++;
        TextView textView = findViewById(R.id.button_tap);
        String value = "Flutter button tapped " + counter + (counter == 1 ? " time" : " times");
        textView.setText(value);
    }

    @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();
    }
}

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 29

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        applicationId "io.flutter.examples.flutter_view"
        minSdkVersion 16
        targetSdkVersion 29
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'com.google.android.material:material:1.0.0'
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  >

  <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"
        android:layout_weight="1"
        android:gravity="center"
        android:textSize="@dimen/font_size"
        />

      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/android"
        android:layout_margin="@dimen/edge_margin"
        android:textSize="@dimen/platform_label_font_size"
        android:background="@color/grey"
        />

    </LinearLayout>

    <com.google.android.material.floatingactionbutton.FloatingActionButton
      android:id="@+id/button"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="bottom|right"
      android:elevation="@dimen/fab_elevation_resting"
      app:pressedTranslationZ="@dimen/fab_elevation_pressed"
      android:layout_margin="@dimen/edge_margin"
      android:src="@drawable/ic_add_black_24dp"
      android:clickable="true"
      app:rippleColor="@color/grey"
      app:fabSize="normal"
      app:backgroundTint="@color/white"
      />

  </androidx.coordinatorlayout.widget.CoordinatorLayout>

</LinearLayout>