如何在Flutter中拥有与服务器发送事件/ EventSource功能类似的功能？

import 'dart:async';
import 'package:http/http.dart' as http;

void startLongPolling() {
  Timer.periodic(Duration(seconds: 5), (Timer t) async {
    final response = await http.get(Uri.parse('https://yourserver.com/events'));
    if (response.statusCode == 200) {
      print('New data: ${response.body}');
    }
  });
}

import 'package:web_socket_channel/web_socket_channel.dart';

void startWebSocket() {
  final channel = WebSocketChannel.connect(
    Uri.parse('wss://yourserver.com/events'),
  );

  channel.stream.listen((message) {
    print('New data: $message');
  }, onError: (error) {
    print('Error: $error');
  });
}

import 'package:sse_client/sse_client.dart';

void startSSE() {
  final client = SSEClient(Uri.parse('https://yourserver.com/events'));

  client.stream.listen((event) {
    print('New data: ${event.data}');
  }, onError: (error) {
    print('Error: $error');
  });
}

import 'package:graphql_flutter/graphql_flutter.dart';

void startGraphQLSubscription() {
  final GraphQLClient client = GraphQLClient(
    link: HttpLink('https://yourserver.com/graphql'),
    cache: InMemoryCache(),
  );

  final QueryOptions options = QueryOptions(
    document: gql('''
      subscription {
        newEvent {
          id
          data
        }
      }
    '''),
  );

  client.subscribe(options).listen((result) {
    print('New data: ${result.data}');
  }, onError: (error) {
    print('Error: $error');
  });
}