Flutter与原生(Android/IOS)的消息通信

开发集成环境
[✓] Flutter (Channel unknown, v1.12.13+hotfix.8, on Mac OS X 10.14.6 18G103, locale zh-Hans-CN)

一、简述Flutter集成到Android原生项目
二、Android原生以AAR形式集成Flutter项目
三、Flutter与原生(Android/IOS)的消息通信
四、Flutter中如何使用原生控件/组件
五、Flutter升级及开发中遇到的问题汇总

前面也谈到除了一些新项目以外，目前大多数都是在原有项目中逐步插入跨平台技术，虽说Flutter提供的插件越来越丰富，但在新项目中的需求也会或多或少涉及到原生的帮助，自然而然又稍微掺杂点混编了。
其实跨平台框架在与原生项目进行混编时，是避免不了两者之间的相互通信，当然也会涉及到对应的页面跳转，仔细想想其实当解决了两者之间的相互通信后，好像页面跳转也不是什么大问题了，只是方式的友好与否而已。

下面分别就Flutter与Android消息通信、Flutter与IOS消息通信两个方面作下简单描述，其中Flutter与Android消息通信涉及Java与Kotlin两种语言、Flutter与IOS消息通信涉及Object-C和Swift两种语言。

一、Flutter与Android的消息通信

1、Android端实现接收消息和发送消息

• Java版

  public class MainActivity extends FlutterActivity {
   @Override
   public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
     GeneratedPluginRegistrant.registerWith(flutterEngine);
     MethodChannel  mc = new MethodChannel(flutterEngine.getDartExecutor(), "com.cc.flutter.native"); //此处名称应与Flutter端保持一致
     //接收Flutter消息
     mc.setMethodCallHandler(new MethodChannel.MethodCallHandler() {
             @Override
             public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
                 System.out.println("MethodChannel call.method:"+call.method+ "  call arguments:"+call.arguments);
                 switch (call.method){
                     case "envType":
                         result.success("2");
                         break;
                     case "toast":
                         String msg = call.argument("msg");
                         Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
                         result.success("成功啦");
                         break;
                     default:
                         result.error("404", "未匹配到对应的方法"+call.method, null);
                 }
             }
         });
   
  //     mc.invokeMethod("aaa", "c")  //发送消息
   }
  }
  

• Kotlin版

  class MainActivity : FlutterActivity(){     
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         var methodChannel = MethodChannel(flutterEngine.dartExecutor, "com.cc.flutter.native")
         methodChannel.setMethodCallHandler { call: MethodCall, result: MethodChannel.Result? ->
             println("MethodChannel call.method:" + call.method + "  call arguments:" + call.arguments)
             when (call.method) {
                 "envType" -> result!!.success("2")
                 "toast" -> {
                     val msg = call.argument<String>("msg")
                     showToast(msg!!)
                     result!!.success("成功啦")
                 }
                 else -> result!!.error("404", "未匹配到对应的方法" + call.method, null)
             }
         }
     }
  }
  

2、Flutter测试实现发送消息和接收消息

class NativeUtils{

  static const String NATIVE_CHANNEL_NAME = "com.cc.flutter.native"; //给native发消息，此处应和客户端名称保持一致
  //channel_name每一个通信通道的唯一标识，在整个项目内唯一！！！
  static const _channel = const MethodChannel(NATIVE_CHANNEL_NAME);

  ///
  /// @Params:
  /// @Desc: 获取native的数据
  ///
  static getNativeData(key,[ dynamic arguments ]) async{
    try {
      String resultValue = await _channel.invokeMethod(key, arguments);
      return resultValue;
    }on PlatformException catch (e){
      print(e.toString());
      return "";
    }
  }
  
   static registerMethod(){
    //接收处理原生消息
    _channel.setMethodCallHandler((handler) {
      switch (handler.method) {
        case "aaa": 
          // 发送原生消息
          _channel.invokeMethod("toast", {"msg": "您调用了dart里的方法"});
          break;
      }
    });
  }
}

1. 在Flutter页面初始化时调用NativeUtils.registerMethod()后，这样客户端调用methodChannel.invokeMethod("aaa", "c") 此时Flutter才能收到对应的消息。
2. 在Flutter页面中调用NativeUtils. getNativeData("envType") 此时才能调用原生客户端对应的方法获取数据。

以上是Flutter与Android端相互通信的部分，下面部分是Flutter与IOS相互通信的部分。

二、Flutter与IOS的消息通信

1. Android端实现接收消息和发送消息

• Object-C版

  #import "AppDelegate.h"
  #include "GeneratedPluginRegistrant.h"
  #import "FlutterNativePlugin.h"
  
  @implementation AppDelegate
  
  - (BOOL)application:(UIApplication *)application
      didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  
      [GeneratedPluginRegistrant registerWithRegistry:self];
      FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;
     
       FlutterMethodChannel* channel = [FlutterMethodChannel methodChannelWithName:@"com.cc.flutter.native" binaryMessenger:controller.binaryMessenger];
     
       [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
           if ([call.method isEqualToString:@"cityId"]) {
               result([NSNumber numberWithInt:1]);
           } if([call.method isEqualToString:@"envType"]){
               result(@"1");
           } else {
             result(FlutterMethodNotImplemented);
         }
     }];
  
    return [super application:application didFinishLaunchingWithOptions:launchOptions];
  }
  
  @end
  

• Swift版

  import UIKit
  import Flutter
  
  @UIApplicationMain
  @objc class AppDelegate: FlutterAppDelegate {
    override func application(
      _ application: UIApplication,
      didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
      GeneratedPluginRegistrant.register(with: self)
  
      let controller:FlutterViewController = window.rootViewController as! FlutterViewController
      let channel = FlutterMethodChannel(name: "com.cc.flutter.native", binaryMessenger: controller.binaryMessenger)
      channel.setMethodCallHandler { (call, result) in
          if "cityId" == call.method{
              result(1);
          }
          else if "envType" == call.method{
              result("1");
          }
          else{
              result(FlutterMethodNotImplemented)
          }
      }    
      return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
  }
  
  

2. Flutter端测试实现发送消息和接收消息代码和Android共用即可。