【Flutter 混合开发】与原生通信-MethodChannel

概述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

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。

平台通信的3中方式

Flutter 与 Native 端通信有如下3个方法：

MethodChannel：Flutter 与 Native 端相互调用，调用后可以返回结果，可以 Native 端主动调用，也可以Flutter主动调用，属于双向通信。此方式为最常用的方式， Native 端调用需要在主线程中执行。BasicmessageChannel：用于使用指定的编解码器对消息进行编码和解码，属于双向通信，可以 Native 端主动调用，也可以Flutter主动调用。EventChannel：用于数据流（event streams）的通信， Native 端主动发送数据给 Flutter，通常用于状态的监听，比如网络变化、传感器数据等。通信架构图

此图为官方的架构图

Flutter 与 Native 端通信是异步的。

通信与平台线程

Native 端主动发送数据给 Flutter时，Native 端代码需要在主线程中执行，AndroID 端从子线程跳转到主线程方式：

Kotlin 代码：

Handler(Looper.getMainLooper()).post {  }

Java 代码：

new Handler(Looper.getMainLooper()).post(new Runnable() {  @OverrIDe  public voID run() {      }});

如果可以获取到当前 Activity，也可以使用如下方式：

activity.runOnUiThread {   }

iOS 端从子线程跳转到主线程方式：

Objective-C 代码：

dispatch_async(dispatch_get_main_queue(),^{  });

Swift 代码：

dispatchQueue.main.async {  }

MethodChannelFlutter 端

Flutter 端创建 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。

发送消息：

var result = await channel.invokeMethod('sendData',{'name': 'laomeng','age': 18})

第一个参数表示method，方法名称，原生端会解析此参数。第二个参数表示参数，类型任意，多个参数通常使用Map。返回 Future，原生端返回的数据。

完整代码：

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','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 下创建 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 方法在 Flutter 端调用 invokeMethod 方法回调，解析方法如下：

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 方法传入的 method。call.argument 是 invokeMethod 传入的参数，由于 Flutter 端传入的是 Map，所以上面的解析按照 Map 解析。result.success() 是返回给 Flutter 的结果。

Flutter 端解析：

var result = await channel    .invokeMethod('sendData','age': 18});var name = result['name'];var age = result['age'];

两端的解析要相互对应。

在 MainActivity 启动：

class MainActivity : FlutterActivity() {        overrIDe fun configureFlutterEngine(FlutterEngine: FlutterEngine) {        super.configureFlutterEngine(FlutterEngine)        MethodChannelDemo(FlutterEngine.dartExecutor.binaryMessenger)    }}

iOS 端

ios 下创建 MethodChannelDemo，按如下方式：

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)  }}

原生端主动发送消息给FlutterFlutter 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)            }        },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,"age" to "$age"            )            result.success(map)        }    }}

注意：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)         }

启动修改如下：

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","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)    }}

交流

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