Android communication after a Flutter update

Current Flutter SDK version (stable, V1.12.13 +hotfix.5)

With the upgrade of Flutter to 1.12, the android code for the new project will be different from the original one, and the way it is written will be slightly different. I saw that the old ones were out of date, so I decided to write a new one

Always error before:

Unhandled Exception: MissingPluginException(No implementation found for method getBatteryLevel on channel com.yn.platform/battery)

Later I found out that the official website is

new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL)

To be replaced by:

new MethodChannel(flutterEngine.getDartExecutor(), CHANNEL)

Inside the setMethodCallHandler () join MethodChannel. MethodCallHandler ()

The Android end

MainActivity.java

package com.yn.platform;

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 androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugins.GeneratedPluginRegistrant;

public class MainActivity extends FlutterActivity {
  private static final String CHANNEL = "com.yn.platform/battery";

  @Override
  public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
    GeneratedPluginRegistrant.registerWith(flutterEngine);
    new MethodChannel(flutterEngine.getDartExecutor(), CHANNEL).setMethodCallHandler(
      new MethodChannel.MethodCallHandler() {
        @Override
        public void onMethodCall(MethodCall call, MethodChannel.Result result) {
          if (call.method.equals("getBatteryLevel")) {
            int batteryLevel = getBatteryLevel();

            if(batteryLevel ! = -1) {
              result.success(batteryLevel);
            } else {
              result.error("UNAVAILABLE"."Battery level not available.".null); }}else{ result.notImplemented(); }}}); }private int getBatteryLevel(a) {
    int batteryLevel = -1;
    if (VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP) {
      BatteryManager batteryManager = (BatteryManager) getSystemService(BATTERY_SERVICE);
      batteryLevel = batteryManager.getIntProperty(BatteryManager.BATTERY_PROPERTY_CAPACITY);
    } else {
      Intent intent = new ContextWrapper(getApplicationContext()).
              registerReceiver(null.new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
      batteryLevel = (intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1) * 100) /
              intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
    }
    returnbatteryLevel; }}Copy the code

The Flutter end

main.dart

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page')); }}class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static const platform = const MethodChannel('com.yn.platform/battery');

  String _batteryLevel = 'Unknown battery level.';

  Future<void> _getBatteryLevel() async {
    String batteryLevel;
    try {
      final int result = await platform.invokeMethod('getBatteryLevel');
      batteryLevel = 'Battery level at $result % .';
    } on PlatformException catch (e) {
      batteryLevel = "Failed to get battery level: '${e.message}'.";
    }

    setState(() {
      _batteryLevel = batteryLevel;
    });
  }


  @override
  void initState() {
    _getBatteryLevel();
  }

  @override
  Widget build(BuildContext context) {
    returnScaffold( appBar: AppBar( title: Text(widget.title), ), body: Center( child: Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ Text( _batteryLevel, ), ], ), ), ); }}Copy the code