原生Android调用Flutter的dart方法
先提供完整的代码
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
);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{
static const _platform = const MethodChannel('toFlutterChannelName');
@override
void initState() {
_platform.setMethodCallHandler(flutterMethod);
super.initState();
}
@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);
},
)
)
),
);
}
Future flutterMethod(MethodCall methodCall) async{
switch (methodCall.method) {
case 'fluMethod':
print('原生Android调用了flutterMethod方法！！！');
print('原生Android传递给flutter的参数是：：'+methodCall.arguments);
break;
}
}
}
MainActivity.java
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";
MethodChannel methodChannel_toFlutter;
@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);
}
//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()
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();
}
}
}
);
methodChannel_toFlutter = new MethodChannel(
getFlutterEngine().getDartExecutor().getBinaryMessenger(), "toFlutterChannelName"
);
}
public String toJava(String name){
System.out.println("传递的参数是"+name);
invokeFlutterMethod_toAllFlutter();
return "您好"+name;
}
public void invokeFlutterMethod_toAllFlutter(){
if (this.methodChannel_toFlutter != null) {
this.methodChannel_toFlutter.invokeMethod("fluMethod", "我是原生Android，我将参数传递给Flutter里面的一个方法", new MethodChannel.Result() {
@Override
public void success(Object o) {
}
@Override
public void error(String s, String s1, Object o) {
}
@Override
public void notImplemented() {
}
});
}
}
}
下面来解释步骤
一、在MainPage类中定义一个MethodChannel常量_platform, 并在initState()方法中处理Flutter申请要调用的method的值，此时会调用自定义方法flutterMethod
在Flutter代码中：
static const _platform = const MethodChannel('toFlutterChannelName');
@override
void initState() {
_platform.setMethodCallHandler(flutterMethod);
super.initState();
}二、定义一个flutterMethod方法
在Flutter代码中：
Future flutterMethod(MethodCall methodCall) async{
switch (methodCall.method) {
case 'fluMethod':
print('原生Android调用了flutterMethod方法！！！');
print('原生Android传递给flutter的参数是：：'+methodCall.arguments);
break;
}
} 三、在原生Android的MainActivity类中，声明一个MethodChannel的变量，然后在onCreate()方法中，通过这个变量获取通道
public class MainActivity extends FlutterActivity {
MethodChannel methodChannel_toFlutter;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
methodChannel_toFlutter = new MethodChannel(
getFlutterEngine().getDartExecutor().getBinaryMessenger(),"toFlutterChannelName"
);
}
}四、让原生Android调用 invokeFlutterMethod_toAllFlutter() 方法，这个方法里面实现了 "调用flutter方法的动作"。
您也可以在onCreate() 里面，直接invokeFlutterMethod_toAllFlutter()调用这个方法，以调用flutter的方法。
public void invokeFlutterMethod_toAllFlutter(){
if (this.methodChannel_toFlutter != null) {
this.methodChannel_toFlutter.invokeMethod("fluMethod", "我是原生Android，我将参数传递给Flutter里面的一个方法", new MethodChannel.Result() {
@Override
public void success(Object o) {
}
@Override
public void error(String s, String s1, Object o) {
}
@Override
public void notImplemented() {
}
});
}
}五、测试
