Flutter--WebSocket_flutter websocket

借助web_socket_channel: ^2.2.0 

 
import 'package:flutter/material.dart';
import 'package:web_socket_channel/io.dart';
 
class SocketPage extends StatefulWidget {
  const SocketPage({Key? key}) : super(key: key);
 
  @override
  State<StatefulWidget> createState() => _SocketState();
 
}
 
class _SocketState extends State<SocketPage> {
 
  final TextEditingController _controller = TextEditingController();
  late IOWebSocketChannel channel;
 
  @override
  void initState() {
    channel = IOWebSocketChannel.connect('wss://echo.websocket.events');
  }
 
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("WebSocket(内容回显)"),
      ),
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Form(
              child: TextFormField(
                controller: _controller,
                decoration: InputDecoration(labelText: 'Send a message'),
              ),
            ),
            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);
    }
  }
 
  @override
  void dispose() {
    channel.sink.close();
    super.dispose();
  }
}