在开发中通常需要 Flutter 端与原生内容进行交互。Flutter 定义了三种不同的Channel,它们分别是
- BasicMessageChannel:用于传递字符串和半结构化的信息
- MethodChannel:用于传递方法调用
- EventChannel:用于数据流的通信
BasicMessageChannel
- 实现插件
public class FlutterPluginBasicTest implements BasicMessageChannel.MessageHandler{
private static final String TAG = "FlutterPluginBasicTest";
public static String CHANNEL = "com.mmd.flutterapp/plugin";
static BasicMessageChannel messageChannel;
public static void registerWith(PluginRegistry.Registrar registrar) {
messageChannel = new BasicMessageChannel(registrar.messenger(),CHANNEL,StandardMessageCodec.INSTANCE);
FlutterPluginBasicTest flutterPluginBasicTest = new FlutterPluginBasicTest();
messageChannel.setMessageHandler(flutterPluginBasicTest);
}
/**
* java 发起通信
* @param string
*/
void sendMessage(String string) {
messageChannel.send(string, new BasicMessageChannel.Reply() {
@Override
public void reply(Object o) {
Log.d(TAG, "reply: "+0);
}
});
}
/**
* Flutter 发起的通信
* @param o
* @param reply
*/
@Override
public void onMessage(Object o, BasicMessageChannel.Reply reply) {
Log.d(TAG, "onMessage: "+o);
reply.reply("ok");
}
}
- 注册
FlutterPluginBasicTest.registerWith(this.registrarFor(FlutterPluginBasicTest.CHANNEL));
- dart 调用
/**
* 发送
*/
Future<String> sendMessage() async{
String reply = await messageChannel.send("Flutter send");
print(reply);
return reply;
}
/**
* 接收
*/
void receiveMessage(){
messageChannel.setMessageHandler((message) async{
print(message);
return "is ok";
});
}
MethodChannel
flutter 调用 原生
- 实现插件
public class FlutterPluginTest implements MethodChannel.MethodCallHandler {
private static final String TAG = "FlutterPluginTest";
/**
* 插件标识
*/
public static String CHANNEL = "com.mmd.flutterapp/plugin";
private static String ACTION_LOG = "log";
private static String LOG_ARGUMENT = "data";
static MethodChannel channel;
public static void registerWith(PluginRegistry.Registrar registrar) {
channel = new MethodChannel(registrar.messenger(), CHANNEL);
FlutterPluginTest instance = new FlutterPluginTest();
channel.setMethodCallHandler(instance);
}
@Override
public void onMethodCall(MethodCall methodCall, MethodChannel.Result result) {
/**
* 通过 method 判断调用方法
*/
if (methodCall.method.equals(ACTION_LOG)) {
/**
* 解析参数
*/
String text = methodCall.argument(LOG_ARGUMENT);
if (TextUtils.isEmpty(text)) {
/**
* 错误返回
*/
result.error("Data is Null",null,null);
}else {
Log.d(TAG, "onMethodCall: "+text);
/**
* 成功返回
*/
result.success("is ok");
}
}else {
result.notImplemented();
}
}
}
- 注册插件
public class MainActivity extends FlutterActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/**
* 注册插件
*/
FlutterPluginTest.registerWith(this.registrarFor(FlutterPluginTest.CHANNEL));
}
}
- Flutter 端调用
import 'package:flutter/services.dart';
/**
* 名称要和Java端一致
*/
const channelName = "com.mmd.flutterapp/plugin";
const methodName = "log";
const MethodChannel channel = MethodChannel(channelName);
Future<String> _testLog() async{
Map<String,String> map = {"data":"Flutter Hello !"};
String result = await channel.invokeMethod(methodName,map);
print(result);
}
EventChannel
原生发送数据到Flutter
- 实现插件
public class FlutterPluginEventTest implements EventChannel.StreamHandler {
private static final String TAG = "FlutterPluginEventTest";
public static String CHANNEL = "com.mmd.flutterapp/plugin";
static EventChannel channel;
public static void registerWith(PluginRegistry.Registrar registrar) {
channel = new EventChannel(registrar.messenger(), CHANNEL);
FlutterPluginEventTest flutterPluginEventTest = new FlutterPluginEventTest();
channel.setStreamHandler(flutterPluginEventTest);
}
@Override
public void onListen(Object o, EventChannel.EventSink eventSink) {
new Thread(new Runnable() {
@Override
public void run() {
while (true) {
try {
Thread.sleep(1000);
eventSink.success(System.currentTimeMillis());
} catch (InterruptedException e) {
eventSink.error("error","error",e.getMessage());
}
}
}
}).start();
}
@Override
public void onCancel(Object o) {
Log.i(TAG, "onCancel: "+o);
}
}
- 注册插件
FlutterPluginEventTest.registerWith(this.registrarFor(FlutterPluginEventTest.CHANNEL));
- Flutter 接收
import 'dart:async';
import 'package:flutter/services.dart';
/**
* 名称要和Java端一致
*/
const channelName = "com.mmd.flutterapp/plugin";
const EventChannel eventChannel = EventChannel(channelName);
StreamSubscription _subcription = null;
void init(void onEvent(String value),Function onError){
if(_subcription == null) {
_subcription = eventChannel.receiveBroadcastStream().listen(onEvent,onError: onError);
}
}
void dispose(){
if(_subcription !=null){
_subcription.cancel();
}
}