flutter websocket 客户端

1、pubspec文件管理Flutter应用程序的assets(资源，如图片、package等)。 在pubspec.yaml中，通过网址“https://pub.dartlang.org/packages/web_socket_channel”确认版本号后，将web_socket_channel （1.0.9或更高版本）添加到依赖项列表。

2、在Android Studio的编辑器视图中查看pubspec时，单击右上角的 Packages get，或者在命令行输入“flutter packages get”；这会将依赖包安装到您的项目。

3、运行以下代码

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

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget{
  @override
  Widget build(BuildContext context){
    final title = 'WebSocket Demo';
    return new MaterialApp(
      title:title,
      home: new MyHomePage(
        title: title,
        channel: new IOWebSocketChannel.connect('ws://echo.websocket.org'),//如果是本地直接使用IP地址而非localhost或127.0.0.1
      ),
    );
  }
}

class MyHomePage extends StatefulWidget{
  final String title;
  final WebSocketChannel channel;

  MyHomePage({Key key,@required this.title,@required this.channel}): super(key: key);

  @override
  _MyHomePageState createState()=> new _MyHomePageState();
}

class _MyHomePageState extends State{
  TextEditingController _controller = new TextEditingController();

  @override
  Widget build(BuildContext context){
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new Padding(
        padding: const EdgeInsets.all(20.0),
        child: new Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            new Form(
              child: new TextFormField(
                controller: _controller,
                decoration: new InputDecoration(labelText: 'Send a message'),
              ),
            ),
            new StreamBuilder(
                stream: widget.channel.stream,
                builder: (context, snapshot){
              return new Padding(
                padding: const EdgeInsets.symmetric(vertical: 24.0),
                child: new Text(snapshot.hasData?'${snapshot.data}':''),
              );
            }),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _sendMessage,
        tooltip: 'Send message',
        child: new Icon(Icons.send),
      ),
    );
  }
  void _sendMessage(){
    if (_controller.text.isNotEmpty){
      widget.channel.sink.add(_controller.text);
      print("send message completed");
    }
  }
  @override
  void dispose(){
    widget.channel.sink.close();
    super.dispose();
  }
}