Flutter 混合开发系列 蕴含如下：
- 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
- 增加 Flutter 到 Android Activity
- 增加 Flutter 到 Android Fragment
- 增加 Flutter 到 iOS
每个工作日分享一篇，欢送关注、点赞及转发。
平台通信的3中形式
Flutter 与 Native 端通信有如下3个办法：
- MethodChannel：Flutter 与 Native 端互相调用，调用后能够返回后果，能够 Native 端被动调用，也能够Flutter被动调用，属于双向通信。此形式为最罕用的形式， Native 端调用须要在主线程中执行。
- BasicMessageChannel：用于应用指定的编解码器对音讯进行编码和解码，属于双向通信，能够 Native 端被动调用，也能够Flutter被动调用。
- EventChannel：用于数据流（event streams）的通信， Native 端被动发送数据给 Flutter，通常用于状态的监听，比方网络变动、传感器数据等。
Flutter 端
Flutter 端创立 MethodChannel 通道，用于与原生端通信：
var channel = BasicMessageChannel('com.flutter.guide.BasicMessageChannel',StandardMessageCodec());com.flutter.guide.BasicMessageChannel 是 BasicMessageChannel 的名称，原生端要与之对应。
发送音讯：
var result = await channel.send({'name': 'laomeng', 'age': 18});- 参数类型任意，多个参数通常应用Map。
- 返回 Future，原生端返回的数据。
残缺代码：
class BasicMessageChannelDemo extends StatefulWidget { @override _BasicMessageChannelDemoState createState() => _BasicMessageChannelDemoState();}class _BasicMessageChannelDemoState extends State<BasicMessageChannelDemo> { var channel = BasicMessageChannel('com.flutter.guide.BasicMessageChannel',StandardMessageCodec()); var _data; @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(), body: Column( children: [ SizedBox( height: 50, ), RaisedButton( child: Text('发送数据到原生'), onPressed: () async { var result = await channel.send({'name': 'laomeng', 'age': 18}); var name = result['name']; var age = result['age']; setState(() { _data = '$name,$age'; }); }, ), Text('原生返回数据：$_data'), ], ), ); }}Android 端
android 下创立 BasicMessageChannelDemo：
class BasicMessageChannelDemo(messenger: BinaryMessenger) : BasicMessageChannel.MessageHandler<Any> { private var channel: BasicMessageChannel<Any> init { channel = BasicMessageChannel(messenger, "com.flutter.guide.BasicMessageChannel", StandardMessageCodec()) channel.setMessageHandler(this) } override fun onMessage(message: Any?, reply: BasicMessageChannel.Reply<Any>) { val name = (message as Map<String, Any>)["name"] val age = (message as Map<String, Any>)["age"] var map = mapOf("name" to "hello,$name", "age" to "$age" ) reply.reply(map) }}onMessage 办法在 Flutter 端调用 send 办法后调用，解析办法如下：
override fun onMessage(message: Any?, reply: BasicMessageChannel.Reply<Any>) { val name = (message as Map<String, Any>)["name"] val age = (message as Map<String, Any>)["age"] var map = mapOf("name" to "hello,$name", "age" to "$age" ) reply.reply(map) }- message 是传入的参数，因为 Flutter 端传入的是 Map，所以下面的解析依照 Map 解析。
- reply.reply() 是返回给 Flutter 的后果。
Flutter 端解析：
var result = await channel.send({'name': 'laomeng', 'age': 18});var name = result['name'];var age = result['age'];两端的解析要互相对应。
在 MainActivity 启动：
class MainActivity : FlutterActivity() { override fun configureFlutterEngine(flutterEngine: FlutterEngine) { super.configureFlutterEngine(flutterEngine) BasicMessageChannelDemo(flutterEngine.dartExecutor.binaryMessenger) flutterEngine.plugins.add(MyPlugin()) }}iOS 端
ios 下创立 MethodChannelDemo，按如下形式：
import Flutterimport UIKitpublic class BasicMessageChannelDemo { var channel:FlutterBasicMessageChannel init(messenger: FlutterBinaryMessenger) { channel = FlutterBasicMessageChannel(name: "com.flutter.guide.BasicMessageChannel", binaryMessenger: messenger) channel.setMessageHandler { (message, reply) in if let dict = message as? Dictionary<String, Any> { let name:String = dict["name"] as? String ?? "" let age:Int = dict["age"] as? Int ?? -1 reply(["name":"hello,\(name)","age":age]) } } } }在 AppDelegate 启动：
import UIKitimport Flutter@UIApplicationMain@objc class AppDelegate: FlutterAppDelegate { override func application( _ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? ) -> Bool { let controller : FlutterViewController = window?.rootViewController as! FlutterViewController MethodChannelDemo(messenger: controller.binaryMessenger) BasicMessageChannelDemo(messenger: controller.binaryMessenger) GeneratedPluginRegistrant.register(with: self) return super.application(application, didFinishLaunchingWithOptions: launchOptions) }}原生端被动发送音讯给Flutter
Flutter 端接收数据
@override void initState() { super.initState(); channel.setMessageHandler((message) { setState(() { _nativeData = message['count']; }); }); }Android 发送数据
原生端启动定时器，每隔一秒向 Flutter 发送数据，Android 端代码：
class BasicMessageChannelDemo(var activity: Activity, messenger: BinaryMessenger) : BasicMessageChannel.MessageHandler<Any> { private var channel: BasicMessageChannel<Any> private var count = 0 init { channel = BasicMessageChannel(messenger, "com.flutter.guide.BasicMessageChannel", StandardMessageCodec()) channel.setMessageHandler(this) startTimer() } fun startTimer() { var timer = Timer().schedule(timerTask { activity.runOnUiThread { var map = mapOf("count" to count++) channel.send(map,object :BasicMessageChannel.Reply<Any>{ override fun reply(reply: Any?) { } }) } }, 0, 1000) } override fun onMessage(message: Any?, reply: BasicMessageChannel.Reply<Any>) { val name = (message as Map<String, Any>)["name"] val age = (message as Map<String, Any>)["age"] var map = mapOf("name" to "hello,$name", "age" to "$age" ) reply.reply(map) }}留神：Android 端发送数据要在主现场中调用，即：
activity.runOnUiThread { var map = mapOf("count" to count++) channel.invokeMethod("timer", map) }
启动批改如下：
class MainActivity : FlutterActivity() { override fun configureFlutterEngine(flutterEngine: FlutterEngine) { super.configureFlutterEngine(flutterEngine) BasicMessageChannelDemo(this,flutterEngine.dartExecutor.binaryMessenger) flutterEngine.plugins.add(MyPlugin()) }}iOS 发送数据
iOS 端启动定时器代码如下：
import Flutterimport UIKitpublic class BasicMessageChannelDemo { var channel:FlutterBasicMessageChannel var count = 0 init(messenger: FlutterBinaryMessenger) { channel = FlutterBasicMessageChannel(name: "com.flutter.guide.BasicMessageChannel", binaryMessenger: messenger) channel.setMessageHandler { (message, reply) in if let dict = message as? Dictionary<String, Any> { let name:String = dict["name"] as? String ?? "" let age:Int = dict["age"] as? Int ?? -1 reply(["name":"hello,\(name)","age":age]) } } startTimer() } func startTimer() { var timer = Timer.scheduledTimer(timeInterval:1, target: self, selector:#selector(self.tickDown),userInfo:nil,repeats: true) } @objc func tickDown(){ count += 1 var args = ["count":count] channel.sendMessage(args) { (reply) in } }}交换
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