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。
通信架构图
此图为官网的架构图
Flutter 与 Native 端通信是异步的。
通信与平台线程
Native 端被动发送数据给 Flutter时，Native 端代码须要在主线程中执行，Android 端从子线程跳转到主线程形式：
Kotlin 代码：
Handler(Looper.getMainLooper()).post { }Java 代码：
new Handler(Looper.getMainLooper()).post(new Runnable() { @Override public void run() { }});如果能够获取到以后 Activity，也能够应用如下形式：
activity.runOnUiThread { }iOS 端从子线程跳转到主线程形式：
Objective-C 代码：
dispatch_async(dispatch_get_main_queue(), ^{ });Swift 代码：
DispatchQueue.main.async { }MethodChannel
Flutter 端
Flutter 端创立 MethodChannel 通道，用于与原生端通信：
var channel = MethodChannel('com.flutter.guide.MethodChannel');com.flutter.guide.MethodChannel 是 MethodChannel 的名称，原生端要与之对应。
发送音讯：
var result = await channel.invokeMethod('sendData',{'name': 'laomeng', 'age': 18})- 第一个参数示意method，办法名称，原生端会解析此参数。
- 第二个参数示意参数，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 MethodChannelDemo extends StatefulWidget { @override _MethodChannelDemoState createState() => _MethodChannelDemoState();}class _MethodChannelDemoState extends State<MethodChannelDemo> { var channel = MethodChannel('com.flutter.guide.MethodChannel'); 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 .invokeMethod('sendData', {'name': 'laomeng', 'age': 18}); var name = result['name']; var age = result['age']; setState(() { _data = '$name,$age'; }); }, ), Text('原生返回数据：$_data') ], ), ); }}Android 端
android 下创立 MethodChannelDemo：
package com.flutter.guideimport io.flutter.plugin.common.BinaryMessengerimport io.flutter.plugin.common.MethodCallimport io.flutter.plugin.common.MethodChannel/** * des: */class MethodChannelDemo(messenger: BinaryMessenger): MethodChannel.MethodCallHandler { private var channel: MethodChannel init { channel = MethodChannel(messenger, "com.flutter.guide.MethodChannel") channel.setMethodCallHandler(this) } override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) { }}onMethodCall 办法在 Flutter 端调用 invokeMethod 办法回调，解析办法如下：
override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) { if (call.method == "sendData") { val name = call.argument("name") as String? val age = call.argument("age") as Int? var map = mapOf("name" to "hello,$name", "age" to "$age" ) result.success(map) }}- call.method 字符串就是 invokeMethod 办法传入的 method。
- call.argument 是 invokeMethod 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。
- result.success() 是返回给 Flutter 的后果。
Flutter 端解析：
var result = await channel .invokeMethod('sendData', {'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) MethodChannelDemo(flutterEngine.dartExecutor.binaryMessenger) }}iOS 端
ios 下创立 MethodChannelDemo，按如下形式：
import Flutterimport UIKitpublic class MethodChannelDemo { init(messenger: FlutterBinaryMessenger) { let channel = FlutterMethodChannel(name: "com.flutter.guide.MethodChannel", binaryMessenger: messenger) channel.setMethodCallHandler { (call:FlutterMethodCall, result:@escaping FlutterResult) in if (call.method == "sendData") { if let dict = call.arguments as? Dictionary<String, Any> { let name:String = dict["name"] as? String ?? "" let age:Int = dict["age"] as? Int ?? -1 result(["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) 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
@overridevoid initState() { super.initState(); channel.setMethodCallHandler((call) { setState(() { _nativeData = call.arguments['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 MethodChannelDemo(var activity: Activity, messenger: BinaryMessenger) : MethodChannel.MethodCallHandler { private var channel: MethodChannel private var count = 0 init { channel = MethodChannel(messenger, "com.flutter.guide.MethodChannel") channel.setMethodCallHandler(this) startTimer() } fun startTimer() { var timer = Timer().schedule(timerTask { activity.runOnUiThread { var map = mapOf("count" to count++) channel.invokeMethod("timer", map) } }, 0, 1000) } override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) { if (call.method == "sendData") { val name = call.argument("name") as String? val age = call.argument("age") as Int? var map = mapOf("name" to "hello,$name", "age" to "$age" ) result.success(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) MethodChannelDemo(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 MethodChannelDemo { var count = 0 var channel:FlutterMethodChannel init(messenger: FlutterBinaryMessenger) { channel = FlutterMethodChannel(name: "com.flutter.guide.MethodChannel", binaryMessenger: messenger) channel.setMethodCallHandler { (call:FlutterMethodCall, result:@escaping FlutterResult) in if (call.method == "sendData") { if let dict = call.arguments as? Dictionary<String, Any> { let name:String = dict["name"] as? String ?? "" let age:Int = dict["age"] as? Int ?? -1 result(["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.invokeMethod("timer", arguments:args) }}交换
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