【Flutter 混合开发】与原生通信-EventChannel

柔情只为你懂 2022-12-18 12:59 259阅读 0赞

![20201026224454842.png][]

> Flutter 混合开发系列 包含如下：
> 
>  *  嵌入原生View-Android
>  *  嵌入原生View-iOS
>  *  与原生通信-MethodChannel
>  *  与原生通信-BasicMessageChannel
>  *  **与原生通信-EventChannel**
>  *  添加 Flutter 到 Android Activity
>  *  添加 Flutter 到 Android Fragment
>  *  添加 Flutter 到 iOS
> 
> 每个工作日分享一篇，欢迎关注、点赞及转发。

### EventChannel ###

#### Flutter 端 ####

Flutter 端创建 **EventChannel** 通道，用于与原生端通信：

var _eventChannel = EventChannel('com.flutter.guide.EventChannel');

**com.flutter.guide.EventChannel** 是 EventChannel 的名称，原生端要与之对应。

监听原生端发送的消息：

var _data;
      @override
      void initState() {
        super.initState();
        _eventChannel.receiveBroadcastStream().listen(_onData);
      }
    
      _onData(event){
        setState(() {
          _data = event;
        });
      }

Flutter 端完整代码：

class EventChannelDemo extends StatefulWidget {
      @override
      _EventChannelDemoState createState() => _EventChannelDemoState();
    }
    
    class _EventChannelDemoState extends State<EventChannelDemo> {
    
      var _eventChannel = EventChannel('com.flutter.guide.EventChannel');
      var _data;
      @override
      void initState() {
        super.initState();
        _eventChannel.receiveBroadcastStream().listen(_onData);
      }
    
      _onData(event){
        setState(() {
          _data = event;
        });
      }
    
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(),
          body: Center(
            child: Text('$_data'),
          ),
        );
      }
    }

#### Android 端 ####

android 下创建 **EventChannelDemo**：

class EventChannelDemo(var activity: Activity, messenger: BinaryMessenger):EventChannel.StreamHandler {
        private var channel: EventChannel
        private var index = 0
        private var events: EventChannel.EventSink? = null
        init {
            channel = EventChannel(messenger, "com.flutter.guide.EventChannel")
            channel.setStreamHandler(this)
            startTimer()
        }
    
    
        fun startTimer() {
            var timer = Timer().schedule(timerTask {
                index++
                var map = mapOf("name" to "laomeng${index}",
                        "age" to "${index}"
                )
                activity.runOnUiThread {
                    events?.success(map)
                }
    
            }, 0, 1000)
    
        }
    
        override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
            this.events = events
        }
    
        override fun onCancel(arguments: Any?) {
            this.events = null
        }
    }

![20201026224455480.png][]

**events?.success(map)** 方法是向 Flutter 端发送数据，此方法必须在主线程执行：

activity.runOnUiThread {
        events?.success(map)
    }

在 **MainActivity** 启动：

class MainActivity : FlutterActivity() {
    
        override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
            super.configureFlutterEngine(flutterEngine)
            EventChannelDemo(this,flutterEngine.dartExecutor.binaryMessenger)
            flutterEngine.plugins.add(MyPlugin())
        }
    }

![2020102622445630.png][]

#### iOS 端 ####

ios 下创建 **MethodChannelDemo**，按如下方式：

import Flutter
    import UIKit
    
    public class EventChannelDemo:NSObject, FlutterStreamHandler{
    
        var channel:FlutterEventChannel?
        var count =  0
        var events:FlutterEventSink?
    
        public override init() {
            super.init()
        }
    
        convenience init(messenger: FlutterBinaryMessenger) {
    
            self.init()
    
            channel = FlutterEventChannel(name: "com.flutter.guide.EventChannel", binaryMessenger: messenger)
            channel?.setStreamHandler(self)
            startTimer()
        }
    
        func startTimer() {
            let timer = Timer.scheduledTimer(timeInterval:1, target: self, selector:#selector(self.tickDown),userInfo:nil,repeats: true)
        }
        @objc func tickDown(){
            count += 1
            let args = ["count":count]
            if(events != nil){
                events!(args)
            }
        }
    
        public func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {
            self.events = events
            return nil;
        }
    
        public func onCancel(withArguments arguments: Any?) -> FlutterError? {
            self.events = nil
            return nil;
        }
    
    }

在 **AppDelegate** 启动：

import UIKit
    import Flutter
    
    @UIApplicationMain
    @objc class AppDelegate: FlutterAppDelegate {
      override func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
      ) -> Bool {
    
        let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
        EventChannelDemo(messenger: controller.binaryMessenger)
        GeneratedPluginRegistrant.register(with: self)
    
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
      }
    }

![20201026224456340.png][]

## 交流 ##

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[20201026224454842.png]: /images/20221122/e9e73a49f4434776ad90d13115051517.png
[20201026224455480.png]: /images/20221122/28e69d22c597478cabfd761e2e46acdc.png
[2020102622445630.png]: /images/20221122/d81ac979960b47fbbdc8e1fd6bdf6c78.png
[20201026224456340.png]: /images/20221122/92b5f5ec57d343f69a235a2822082e29.png
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