Flutter调用原生Android的Java方法

淩亂°似流年 2022-11-26 07:38 350阅读 0赞

# 一、编写main.dart #

import 'package:flutter/material.dart';
    
    import 'MainPage.dart';
    
    void main(){
      runApp(
         MyApp()
      );
    }
    
    class MyApp extends StatelessWidget {
    
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'default',
          theme: defaultTheme,
          home: MainPage(),
        );
      }
    }
    
    
    final ThemeData defaultTheme = ThemeData(
        primaryColor: Colors.lightBlue
    );

# 二、编写MainPage.dart #

import 'package:flutter/cupertino.dart';
    import 'package:flutter/material.dart';
    import 'package:flutter/services.dart';
    
    class MainPage extends StatefulWidget{
      @override
      MainPageState createState()  => MainPageState();
    }
    
    class MainPageState extends State<MainPage>{
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter调用原生Android的方法',
          debugShowCheckedModeBanner: false,
          home: Scaffold(
            appBar: AppBar(
              title: Text('Flutter调用原生Android的Java方法'),
            ),
            body: Center(
              child:
              RaisedButton(
                child:
                Padding(
                  padding: EdgeInsets.only(left: 20,right: 20,top: 20,bottom: 20),
                  child: Text('点击按钮调用原生Android的Java方法\n，返回值在控制台输出'),
                ),
    
                onPressed: ()async{
                  const platform = const MethodChannel("toJava");
                  String returnValue = await platform.invokeMethod("张三");
                  print("从原生Android的java方法返回的值是："+returnValue);
                },
              )
            )
          ),
        );
      }
    
    }

# 三、编写MainActivity类 #

注意事项：
    新版的Flutter SDK默认使用的是 import io.flutter.embedding.android.FlutterActivity; 包，
    则在MethodChannel方法中的第一个参数填写 getFlutterEngine().getDartExecutor().getBinaryMessenger()
    如果你使用的Flutter的SDK是旧版本，那么默认的是 import io.flutter.app.FlutterActivity; 包
    则MethodChannel方法中的第一个参数填写 getFlutterView()

package com.example.flutterTojava;
    
    import android.os.Bundle;
    import android.os.StrictMode;
    
    import io.flutter.embedding.android.FlutterActivity;
    import io.flutter.plugin.common.BinaryMessenger;
    //import io.flutter.app.FlutterActivity;
    import io.flutter.plugin.common.MethodCall;
    import io.flutter.plugin.common.MethodChannel;
    
    public class MainActivity extends FlutterActivity {
    
        private static final String channel = "toJava";
    
        @Override
        protected void onCreate(Bundle savedInstanceState){
            super.onCreate(savedInstanceState);
            if (android.os.Build.VERSION.SDK_INT > 9) {
                StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
                StrictMode.setThreadPolicy(policy);
            }
    
            new MethodChannel(getFlutterEngine().getDartExecutor().getBinaryMessenger(),channel).setMethodCallHandler(
                    new MethodChannel.MethodCallHandler() {
                        @Override
                        public void onMethodCall(MethodCall methodCall, MethodChannel.Result result) {
                            if (methodCall.method!=null) {
                                result.success(toJava(methodCall.method));
                            } else {
                                result.notImplemented();
                            }
                        }
                    }
            );
        }
    
    
        public String toJava(String name){
            System.out.println("传递的参数是"+name);
            return "您好"+name;
        }
    
    }

# 四、控制台输出 #

![20200810212144155.png][]

[20200810212144155.png]: /images/20221124/c41a8b009cca466b884322608064af61.png