Java网络编程（8） - 怎么样使用NettyUDP协议通信？怎么样使用Netty的WebSocket通信案例？

Netty使用UDP协议通信案例

      UDP（User Datagram Protocol）即用户数据包协议，是OSI（Open Sysem Interconnection，开放式系统互联）模型的一种无连接的传输层协议，提供面向事务的简单不可靠信息传输服务。

      在网络中与TCP协议一样，用于处理数据包，是一种无连接信息，不关系数据包，只关注是否发出数据包，UDP有不提供数据包分组、组装，和不能对数据包进行排序的缺点。也就是说，当报文发送之后，是无法得知是否安全完整到达的。

      UDP用来支持那些需要在计算机之间传输数据的网络应用，比如视频会议系统在内的众多C/S模式的网络应用都需要使用UDP协议。

import io.netty.bootstrap.Bootstrap; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelOption; import io.netty.channel.EventLoopGroup; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.DatagramPacket; import io.netty.channel.socket.nio.NioDatagramChannel; import io.netty.util.CharsetUtil;   /**  * Netty UDP协议-服务端  */ public class N04UDPServer {     public static void main(String[] args) throws Exception {          //UDP和Tcp不同，不关心数据包是否达到目的地          EventLoopGroup eventLoopGroup = new NioEventLoopGroup();                   //启动类          Bootstrap bootstrap = new Bootstrap();          bootstrap.group(eventLoopGroup) //绑定链接类                       .channel(NioDatagramChannel.class) //模式                       .option(ChannelOption.SO_BROADCAST, true) //广播                       .handler(new UdpServerHandler()); //数据处理类                   //绑定端口          ChannelFuture channelFuture = bootstrap.bind(1111).sync();          channelFuture.channel().closeFuture().await();                   //关闭          eventLoopGroup.shutdownGracefully();     } } /**  * 服务端数据处理  */ class UdpServerHandler extends SimpleChannelInboundHandler {       /*      * 接收数据的处理      */     @Override     protected void messageReceived(ChannelHandlerContext ctx, DatagramPacket packet) throws Exception {          String data = packet.content().toString(CharsetUtil.UTF_8);          System.out.println("服务端：接收到的数据 - " + data);                   //回传消息          ctx.writeAndFlush(new DatagramPacket(Unpooled.copiedBuffer("收到数据。",CharsetUtil.UTF_8),packet.sender()));     }         @Override     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {          cause.printStackTrace();     } }

import java.net.InetSocketAddress;   import io.netty.bootstrap.Bootstrap; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelOption; import io.netty.channel.EventLoopGroup; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.DatagramPacket; import io.netty.channel.socket.nio.NioDatagramChannel; import io.netty.util.CharsetUtil;   /**  * Netty UDP协议-客户端  */ public class N04UDPClient {     public static void main(String[] args) throws Exception {          //发数据          EventLoopGroup eventLoopGroup = new NioEventLoopGroup();                   //启动类          Bootstrap bootstrap = new Bootstrap();          bootstrap.group(eventLoopGroup) //绑定                       .channel(NioDatagramChannel.class) //模式                       .option(ChannelOption.SO_BROADCAST, true) //广播                       .handler(new UdpClientHandler()); //处理类                   //绑定广播          ChannelFuture channelFuture = bootstrap.bind(0).sync();                   //写出端口和广播掩码地址          channelFuture.channel().writeAndFlush(new DatagramPacket(Unpooled.copiedBuffer("你好啊", CharsetUtil.UTF_8),                                                   new InetSocketAddress("255.255.255.255",1111))).sync();                   //关闭          eventLoopGroup.shutdownGracefully();     } } class UdpClientHandler extends SimpleChannelInboundHandler {       @Override     protected void messageReceived(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {          String data = msg.content().toString(CharsetUtil.UTF_8);          System.out.println(data);     }         @Override     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {          cause.printStackTrace();     } }

 

Netty使用WebSocket通信案例

      WebSocket将网络套接字引入到了客户端和服务端，众所周知，之前实现聊天功能，可能需要古老的Socket技术，或者是古老的DWR框架，反之Ajax技术，在有可能就是Comet服务器推技术，HT的WebSocket可以很轻松的进行聊天功能实现，Netty和H5的WebSocket结合非常的简单，Netty为我们封装了其协议类。

 

WebSocket特点

      单一的TCP链接，双方即可通信。

      对代理、防火墙和路由是透明的。

      无头部信息，Cookie和身份验证。

      无安全开销。

      通过ping/pong帧保持链路激活。

      服务器可主动传递消息给客户端，不在需要客户端轮询。

import java.util.Date;   import io.netty.bootstrap.ServerBootstrap; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInitializer; import io.netty.channel.EventLoopGroup; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioServerSocketChannel; import io.netty.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpRequest; import io.netty.handler.codec.http.HttpHeaderUtil; import io.netty.handler.codec.http.HttpObjectAggregator; import io.netty.handler.codec.http.HttpResponseStatus; import io.netty.handler.codec.http.HttpServerCodec; import io.netty.handler.codec.http.HttpVersion; import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame; import io.netty.handler.codec.http.websocketx.PingWebSocketFrame; import io.netty.handler.codec.http.websocketx.PongWebSocketFrame; import io.netty.handler.codec.http.websocketx.TextWebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory; import io.netty.util.CharsetUtil;   /**  * WebSocket服务端  */ public class N05WebSocketServer {     public static void main(String[] args) throws Exception {          //建立连接和传输数据          EventLoopGroup connectEventLoopGroup = new NioEventLoopGroup();          EventLoopGroup dataEventLoopGroup = new NioEventLoopGroup();                   //启动类          ServerBootstrap serverBootstrap = new ServerBootstrap();          serverBootstrap.group(connectEventLoopGroup, dataEventLoopGroup) //绑定                           .channel(NioServerSocketChannel.class) //模式                           .childHandler(new ChannelInitializer() {                                @Override                                protected void initChannel(SocketChannel ch) throws Exception {                                    ch.pipeline().addLast("http-codec",new HttpServerCodec());                                    ch.pipeline().addLast("aggregator",new HttpObjectAggregator(65535));                                    ch.pipeline().addLast("handler",new WebSocketHandler()); //处理类                                }                           });                   //绑定端口          ChannelFuture channelFuture = serverBootstrap.bind(1111).sync();          channelFuture.channel().closeFuture().sync();                   //关闭          connectEventLoopGroup.shutdownGracefully();          dataEventLoopGroup.shutdownGracefully();     } } class WebSocketHandler extends SimpleChannelInboundHandler

DOCTYPE html> <html> <head> <meta charset="UTF-8"> Netty WebSocket 时间服务器 head> <br> <body> <br> <script type="text/javascript"> var socket; if (!window.WebSocket) {     window.WebSocket = window.MozWebSocket; } if (window.WebSocket) {     socket = new WebSocket("ws://localhost:1111/websocket");     socket.onmessage = function(event) {          var ta = document.getElementById('responseText');          ta.value="";          ta.value = event.data     };     socket.onopen = function(event) {          var ta = document.getElementById('responseText');          ta.value = "打开WebSocket服务正常，浏览器支持WebSocket!";     };     socket.onclose = function(event) {          var ta = document.getElementById('responseText');          ta.value = "";          ta.value = "WebSocket 关闭!";     }; } else {     alert("抱歉，您的浏览器不支持WebSocket协议!"); }   function send(message) {     if (!window.WebSocket) { return; }     if (socket.readyState == WebSocket.OPEN) {          socket.send(message);     } else {            alert("WebSocket连接没有建立成功!");     } } script> <form onsubmit="return false;"> <input type="text" name="message" value="Netty最佳实践"/> <br><br> <input type="button" value="发送WebSocket请求消息" onclick="send(this.form.message.value)"/> <hr color="blue"/> <h3>服务端返回的应答消息h3> <textarea id="responseText" style="width:500px;height:300px;">textarea> form> body> html>