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Flutter——最详细原生交互（MethodChannel、EventChannel、BasicMessageChannel）使用教程

news 来源：原创 2025/6/21 9:58:56

MethodChannel（方法通道）
用途：实现双向通信，用于调用原生平台提供的 API 并获取返回结果。
场景：适合一次性操作，如调用相机、获取设备信息等。

使用步骤：

Flutter 端：通过 MethodChannel监听事件流。

  static const platform =
      MethodChannel('com.example.fltest.plugin.DeviceInfoPlugin');

Android 端（Kotlin）

    private var methodChannel: MethodChannel? = null
  val CHANNEL: String = "com.example.fltest.plugin.DeviceInfoPlugin"
  
  private fun getPhoneNumber(): Any? {
        val telephonyManager = context.getSystemService(Context.TELEPHONY_SERVICE) as TelephonyManager?
//        val phoneNumber = telephonyManager!!.line1Number
        val phoneNumber = "18627000332"
        return phoneNumber
    }

EventChannel（事件通道）
用途：实现单向数据流，用于原生平台向 Flutter 持续发送事件（如传感器数据）。
场景：适合实时数据流，如监听陀螺仪、GPS 位置更新等。
使用步骤：

Flutter 端：通过 EventChannel 监听事件流。

static const eventChannel =
      EventChannel('com.example.fltest.plugin.DeviceInfoPlugin/event');

  Stream<int> get _batteryLevelStream {
    return eventChannel.receiveBroadcastStream("111").cast<int>();
  }

Android 端（Kotlin）

 
class DeviceInfoPlugin(var context: Context) : EventChannel.StreamHandler, FlutterPlugin {

    private var eventChannel: EventChannel? = null
    val EVENT_CHANNEL: String = "com.example.fltest.plugin.DeviceInfoPlugin/event"

    override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
            result.notImplemented()
    }

    override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        setupChannels(binding.binaryMessenger, binding.applicationContext)
    }

    override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        teardownChannels()
    }

    private fun setupChannels(messenger: BinaryMessenger, context: Context) {
        this.context = context
        eventChannel = EventChannel(messenger, EVENT_CHANNEL)
        eventChannel?.setStreamHandler(this)
    }

    private fun teardownChannels() {
        eventChannel?.setStreamHandler(null)
        eventChannel = null
    }

    private val mainHandler = Handler(Looper.getMainLooper())

    override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
        Toast.makeText(context, arguments.toString(), Toast.LENGTH_SHORT).show()
        events?.let {
            sendBatteryLevel(it)
            events.success(1)
            mainHandler.postDelayed({
                events.success(2)
            }, 2000)
            mainHandler.postDelayed({ events.success(3) }, 4000)
        }
    }

    override fun onCancel(arguments: Any?) {

    }

    private fun sendBatteryLevel(events: EventChannel.EventSink) {
        val batteryLevel = -1
        if (batteryLevel != -1) {
            events.success(batteryLevel)
        } else {
            events.error("UNAVAILABLE", "Battery level not available.", null);
        }
    }
}

BasicMessageChannel（基础消息通道）
用途：支持异步消息传递，使用自定义编解码器传递数据。
场景：适合简单的数据交换（如 JSON、二进制数据）。

使用步骤：

Flutter 端：通过 BasicMessageChannel监听事件流。

  final BasicMessageChannel<String> messageChannel =
      BasicMessageChannel<String>(
    'com.example.fltest.plugin.DeviceInfoPlugin/basicMessage',
    StringCodec(),
  );
  
// 发送消息
Future<String> sendMessage(String message) async {
  return await messageChannel.send(message);
}

    @override
  void initState() {
    super.initState();
    // 设置消息处理器
    messageChannel.setMessageHandler((String? message) async {
      print('Received message from native: $message');
      return '$message';
    });
  }

Android 端（Kotlin）

package com.example.fltest.plugin

import android.content.Context
import android.os.Handler
import android.os.Looper
import android.telephony.TelephonyManager
import android.widget.Toast
import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.plugin.common.BasicMessageChannel
import io.flutter.plugin.common.BasicMessageChannel.Reply
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.EventChannel
import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
import io.flutter.plugin.common.MethodChannel.MethodCallHandler
import io.flutter.plugin.common.StandardMessageCodec
import io.flutter.plugin.common.StringCodec


class DeviceInfoPlugin(var context: Context) :  FlutterPlugin {

    private var basicMessageChannel: BasicMessageChannel<String>? = null
    val BASIC_MESSAGE_CHANNEL: String = "com.example.fltest.plugin.DeviceInfoPlugin/basicMessage"

    override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
      
            result.notImplemented()
       
    }

    override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        setupChannels(binding.binaryMessenger, binding.applicationContext)
    }

    override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        teardownChannels()
    }

    private fun setupChannels(messenger: BinaryMessenger, context: Context) {
        this.context = context
        basicMessageChannel = BasicMessageChannel(messenger, BASIC_MESSAGE_CHANNEL, StringCodec.INSTANCE)
        basicMessageChannel?.setMessageHandler { message, reply ->
            println("Received message from Flutter: $message")
            reply.reply("Message received")
            basicMessageChannel?.send(message
            ) { reply -> Toast.makeText(context, reply.toString(), Toast.LENGTH_SHORT).show() }
        }
        // 发送消息
basicMessageChannel.send("Hello from Android") { reply ->
    Log.d("TAG", "Reply: $reply")
}
    }

    private fun teardownChannels() {
       
    }
    
    override fun onCancel(arguments: Any?) {

    }

}

在MainActivity初始化添加插件类

package com.example.fltest

import com.example.fltest.plugin.DeviceInfoPlugin
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine

class MainActivity: FlutterActivity(){
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        flutterEngine.plugins.add(DeviceInfoPlugin(this))
    }
}

总结：

方法	方向	使用场景
MethodChannel	双向	调用原生 API 并获取结果
EventChannel	单向（原生→Flutter）	监听持续事件（如传感器）
BasicMessageChannel	双向	简单消息传递（字符串、二进制数据）

根据具体需求选择合适的方式，可覆盖绝大多数跨平台交互场景。