Flutter发送UDP包

见下面代码

import 'dart:io';

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Lighting controller'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {


  void _open() {
    setState(() {
      RawDatagramSocket.bind(InternetAddress.ANY_IP_V4, 0)
          .then((RawDatagramSocket socket) {
        print('Sending from ${socket.address.address}:${socket.port}');
        int port = 4000;
        socket.send('open'.codeUnits,
            InternetAddress("192.168.205.240"), port);
      });
    });
  }

   void _close() {
    setState(() {
      RawDatagramSocket.bind(InternetAddress.ANY_IP_V4, 0)
          .then((RawDatagramSocket socket) {
        print('Sending from ${socket.address.address}:${socket.port}');
        int port = 4000;
        socket.send('close'.codeUnits,
            InternetAddress("192.168.205.240"), port);
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            FlatButton(
              color: Colors.blue,
              highlightColor: Colors.blue[700],
              colorBrightness: Brightness.dark,
              splashColor: Colors.grey,
              padding: EdgeInsets.fromLTRB(40, 20, 40, 20),
              child: Text("开",
                style: TextStyle(
                  fontSize: 40,
                ),
              ),
              shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(20.0)),
              onPressed: _open,
            ),
            Padding(
              padding: new EdgeInsets.fromLTRB(10, 100, 10, 10),
            ),
            FlatButton(
              color: Colors.red,
              highlightColor: Colors.red[700],
              colorBrightness: Brightness.dark,
              splashColor: Colors.grey,
              padding: EdgeInsets.fromLTRB(40, 20, 40, 20),
              child: Text("关",
                style: TextStyle(
                  fontSize: 40,
                ),
              ),
              shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(20.0)),
              onPressed: _close,
            ),
          ],
        ),
      ),
     
    );
  }
}

微信图片_20190809172619.png