Flutter与Android通信 记录

使用MethodChannel方式通信

在建 好工程以后,发现android的工程as识别不了.问题就来了,我要写kotlin或java代码没有提示.

打开,project structure->modules,右侧应该可以看到项目的目录了.

看图,将java目录选为source,res选为resouces.

然后选择上面的dependenciestab,在底部会看到+号:

 

在弹出的窗口中选择new library.进入jar文件选择.flutter的安装目录下.

• flutter/bin/cache/artifacts/engine/android-arm/flutter.jar

这里有好多个jar,我随便选择了一个,只是支持的cpu架构不同.选完以后就可以高亮提示了.

开始通信:

在MainActivity extends FlutterActivity中.

private MethodChannel mMethodChannel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        GeneratedPluginRegistrant.registerWith(this);

        flutterView = getFlutterView();

        methodChannelFunc();
    }

    private void methodChannelFunc() {
//flutter_and_native_mc 这个名字就是通信标识.flutter端要一致.
        mMethodChannel = new MethodChannel(flutterView, "flutter_and_native_mc");
        
        mMethodChannel.setMethodCallHandler(
                new MethodChannel.MethodCallHandler() {
                    @Override
                    public void onMethodCall(MethodCall call, MethodChannel.Result result) {
                        String method = call.method;

                        if (method.equals("method1")) {
                            Toast.makeText(mContext, "flutter 调用到了 android method1", Toast.LENGTH_SHORT).show();
                            Map resultMap = new HashMap<>();
                            resultMap.put("message", "android 调用 flutter method1方法");
                            mMethodChannel.invokeMethod("method1", resultMap,
                                    new MethodChannel.Result() {
                                        @Override
                                        public void success(Object o) {
                                            Log.d("tag", "msg:" + o);
                                        }

                                        @Override
                                        public void error(String s, String s1, Object o) {
                                            Log.d("tag", "error:" + s + " s1:" + s1 + " o:" + o);
                                        }

                                        @Override
                                        public void notImplemented() {

                                        }
                                    });
                        } else if (method.equals("method2")) {
                            String args = call.argument("test_key");
                            if (!TextUtils.isEmpty(args)) {
                                Log.d("tag", "args:" + args);
                            }
                            Map resultMap = new HashMap<>();
                            resultMap.put("message", "native 接收到了参数:" + args);
                            resultMap.put("code", 200);
                            result.success(resultMap);
//这里通过result.success与下面的不一样.
                            mMethodChannel.invokeMethod("method2", resultMap);
                        } else {
                            result.notImplemented();
                        }
                    }
                }
        );
    }
native部分就完成了.比较简单的.

flutter部分
建一个StatefulWidget.
state里:
static const methodChannel = const MethodChannel('flutter_and_native_mc');
static Future invokNative(String method, {Map args}) async {
    if (args == null) {
      return await methodChannel.invokeMethod(method);
    } else {
      return await methodChannel.invokeMethod(method, args);
    }
  }

  Future callHandler(MethodCall call) async {
    String method = call.method;
    switch (call.method) {
      case "method1":
        Map arguments = call.arguments;

        String message = arguments["message"];
        setState(() {
          str += "method1:$method, message:$message \n";
          print(str);
        });
        break;
      case "method2":
        Map arguments = call.arguments;

        String message = arguments["message"];
        setState(() {
          str += "method2:$method, message:$message \n";
          print(str);
        });
        break;
    }
  }

//注册:
  void registMessageListener() {
    methodChannel.setMethodCallHandler(callHandler);
  }
  @override
  void initState() {
    super.initState();

    registMessageListener();
  }

把widget用ListView组合起来就行了:
@override
  Widget build(BuildContext context) {
    return Scaffold(
      body: buildWidget(context),
    );
  }

  buildWidget(BuildContext context) {
    return ListView(
      children: [
        Column(
          mainAxisSize: MainAxisSize.max,
          children: [
            Padding(
              padding: EdgeInsets.all(4),
              child: FlatButton(
                  color: Colors.grey,
                  onPressed: () {
                    Map args = Map();
                    args["test_key"] = "test_value";
                    invokNative("method2", args: args)
                      ..then((result) {
                        String message = result["message"];
                        setState(() {
                          str += "native 中的回调  message $message \n";
                        });
                      });
                  },
                  child: Text(
                    "发送消息带参数的",
                    style: TextStyle(color: Colors.white),
                  )),
            ),
            Padding(
              padding: EdgeInsets.all(10),
              child: Text(
                "接收到的消息 $str",
                style: TextStyle(color: Colors.blue, fontSize: 14),
              ),
            ),
          ],
        )
      ],
    );

这时,会接收到两个值.一个是这里的then,有返回,这个返回值是由native的result.success(resultMap);部分得到的
另一个是callHandler里面得到的,这部分是native的mMethodChannel.invokeMethod("method2", resultMap);发出的.

需要注意不同的反馈方式.