如何从Flutter安卓的PlatformView获取活动

import android.app.Activity
import android.content.Context
import android.view.View
import io.flutter.plugin.platform.PlatformView

class MyPlatformView(context: Context) : PlatformView {
    private val view: View = View(context)

    override fun getView(): View {
        return view
    }

    override fun dispose() {}

    fun getActivity(): Activity? {
        return view.context as? Activity
    }
}

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class MyPlatformView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    if (defaultTargetPlatform == TargetPlatform.android) {
      return AndroidView(
        viewType: 'myPlatformView',
        onPlatformViewCreated: (int id) {
          MethodChannel('myPlatformView').invokeMethod('getActivity');
        },
      );
    }
    return Text('Platform view is not supported on this platform.');
  }
}

class MyPlatformViewPlugin(private val registrar: PluginRegistry.Registrar) : PlatformViewFactory(StandardMessageCodec.INSTANCE) {
    override fun create(context: Context, id: Int, args: Any?): PlatformView {
        return MyPlatformView(context)
    }
}

class MyPlatformViewPluginRegistrar(private val registrar: PluginRegistry.Registrar) : PluginRegistry.RegistrarWrapper(registrar) {
    override fun platformViewRegistry(): PlatformViewRegistry {
        return PlatformViewRegistry.getInstance(registrar.messenger()).also { registry ->
            registry.registerViewFactory("myPlatformView", MyPlatformViewPlugin(registrar))
        }
    }
}

class MainActivity : FlutterActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        flutterEngine.plugins.add(MyPlatformViewPluginRegistrar(this))
    }
}