如何创建运行在Flutter应用中的websocket服务器？

dependencies:
  flutter:
    sdk: flutter
  web_socket_channel: ^2.0.0

import 'dart:io';
import 'dart:convert';

void main() async {
  final port = 8080;

  HttpServer.bind(InternetAddress.anyIPv4, port).then((server) {
    print('WebSocket server listening on port $port');

    server.listen((HttpRequest request) {
      if (request.uri.path == '/ws') {
        handleWebSocket(request);
      } else {
        request.response.statusCode = HttpStatus.forbidden;
        request.response.close();
      }
    });
  }).catchError((error) {
    print('Failed to bind to port $port: $error');
  });
}

void handleWebSocket(HttpRequest request) {
  if (WebSocketTransformer.isUpgradeRequest(request)) {
    WebSocketTransformer.upgrade(request).then((webSocket) {
      handleWebSocketConnection(webSocket);
    }).catchError((error) {
      print('Failed to upgrade connection: $error');
    });
  } else {
    request.response.statusCode = HttpStatus.badRequest;
    request.response.close();
  }
}

void handleWebSocketConnection(WebSocket webSocket) {
  print('WebSocket connection established');

  webSocket.listen((message) {
    print('Received message: $message');
    // Echo the message back to the client
    webSocket.add(message);
  }, onDone: () {
    print('WebSocket connection closed');
  }, onError: (error) {
    print('WebSocket error: $error');
  });
}

dart main.dart

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: WebSocketExample(),
    );
  }
}

class WebSocketExample extends StatefulWidget {
  @override
  _WebSocketExampleState createState() => _WebSocketExampleState();
}

class _WebSocketExampleState extends State<WebSocketExample> {
  final TextEditingController _controller = TextEditingController();
  final WebSocketChannel _channel = WebSocketChannel.connect(
    Uri.parse('ws://localhost:8080/ws'),
  );

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('WebSocket Example'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            TextField(
              controller: _controller,
              decoration: InputDecoration(labelText: 'Send a message'),
            ),
            SizedBox(height: 24),
            StreamBuilder(
              stream: _channel.stream,
              builder: (context, snapshot) {
                return Text(snapshot.hasData ? '${snapshot.data}' : '');
              },
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _sendMessage,
        tooltip: 'Send message',
        child: Icon(Icons.send),
      ),
    );
  }

  void _sendMessage() {
    if (_controller.text.isNotEmpty) {
      _channel.sink.add(_controller.text);
      _controller.clear();
    }
  }

  @override
  void dispose() {
    _channel.sink.close();
    super.dispose();
  }
}