我想有一个dart后台服务永远运行（隔离），它将通过websockets与服务器通信。我有一个Android API，它收集信息发送到服务器。我如何调用Android方法，它使用回调和后台隔离的一切？

• • 编辑**

到目前为止，我在dart中创建了一个Isolate，用于定期在后台调用poolSong方法，即使用户正在使用另一个应用程序或屏幕已关闭。
但这给了我下面的错误...关于github的问题，他们说我不能从不同的隔离群发送平台消息，除非它是主隔离群。但如果我从主隔离群发送，当用户退出应用程序时，该隔离群也将终止。

主 dart

class _MyHomePageState extends State<MyHomePage> {
    final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();
    static const platform = const MethodChannel('mainService');

    static _poolSong(SendPort sendPort) async {
        const oneSec = const Duration(seconds:1);
        new Timer.periodic(oneSec, (Timer t) => platform.invokeMethod('poolSong'));
    }

    @override
    void initState() {
        super.initState();
        ReceivePort receivePort = ReceivePort();
        Isolate.spawn(_poolSong, receivePort.sendPort);
    }
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主活动Java

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

    new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
        (call, result) -> {
            if (call.method.equals("startService"))
                startService();
            if (call.method.equals("poolSong"))
                poolSong();
        }
    );
}

错误

E/flutter (25412): [ERROR:flutter/runtime/dart_isolate.cc(717)] Isolate (765499726) 'main.dart:_poolSong()' exited with an error
E/flutter (25412): [ERROR:flutter/shell/common/shell.cc(186)] Dart Error: Unhandled exception:
E/flutter (25412): error: native function 'Window_sendPlatformMessage' (4 arguments) cannot be found
E/flutter (25412): #0   Window.sendPlatformMessage (dart:ui/window.dart:811:9)
E/flutter (25412): #1   BinaryMessages._sendPlatformMessage (package:flutter/src/services/platform_messages.dart:39:15)
E/flutter (25412): #2   BinaryMessages.send (package:flutter/src/services/platform_messages.dart:87:12)
E/flutter (25412): #3   MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:286:49)
E/flutter (25412): <asynchronous suspension>
E/flutter (25412): #4   _MyHomePageState._poolSong.<anonymous closure> (package:musictie/main.dart:37:54)
E/flutter (25412): #5   _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
E/flutter (25412): #6   _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
E/flutter (25412): #7   _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)