调用函数并将参数从 Kotlin 传递到 Flutter

Question

我正在尝试从到PlatformChannels进行通信。实际上尝试按照 flutter 平台频道的文档中的说明进行操作，但方向相反：KotlinFlutter

flutter 平台频道文档

这个想法是从 MainActivity.kt 类上的 configureFlutterEngine 函数调用 Flutter 函数。

为此，我在 Flutter 方面执行了 main.dart（Flutter 的默认示例）：

   class _MyHomePageState extends State<MyHomePage> {

  static const platformChannel = const MethodChannel('myTestChannel');


  @override
  Widget build(BuildContext context) {

    platformChannel.setMethodCallHandler((call){
      print("Hello from ${call.method}");
      return null;
    });


    //
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          //
          //
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
          ],
        ),
      ),
    );
  }
}

从Kotlin 方面，我只是尝试在MainActivity.kt上调用 flutter 回调方法：

override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine)

        val channel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "myTestChannel")

        channel.invokeMethod("myTestChannel","the argument from Android")
}

但是当我运行代码时，Flutter 端没有打印任何内容。也没有崩溃或异常。

Answer 1

您应该按以下方式实施

飞镖代码

method_channel_helper.dart

class AmazonFileUpload {
  static const platform = const MethodChannel('amazon');
  static StreamController<String> _controller = StreamController.broadcast();

  static Stream get streamData => _controller.stream;

  Future<BaseResponse> uploadFile() async {
    try {
      platform.setMethodCallHandler((call) {
        switch (call.method) {
          case "callBack":
            _controller.add("");
            break;
        }
      });
      final Map result = await platform.invokeMethod('s3_upload');
      return BaseResponse(result["success"], result["error"], "");
    } on PlatformException catch (e) {
      return BaseResponse(false, e.message, "");
    }
  }
}

主页.dart

class _HomePageState extends State<HomePage> {

  @override
  void initState() {
    super.initState();
    AmazonFileUpload.streamData.listen((event) {
      print("========$callbackFromKotlinToDart--------");
    });
    AmazonFileUpload().uploadFile();



  @override
  Widget build(BuildContext context) {

}

安卓代码

class MainActivity : FlutterActivity(), TransferListener {
    private val CHANNEL = "amazon"

    var methodResult: MethodChannel.Result? = null
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
        val channel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL)

        channel.setMethodCallHandler { call, result ->
            methodResult = result
            if (call.method == "s3_upload") {
                //Add you login here 
                channel.invokeMethod("callBack", "data1")



            }
        }

    }