Netty实现WebSocket通信案例

Netty开发服务端，HTML实现客户端，实现服务端与客户端的实时交互。

1.存储整个工程的全局配置：

package com.research.netty.WebSocket; import io.netty.channel.group.ChannelGroup; import io.netty.channel.group.DefaultChannelGroup; import io.netty.util.concurrent.GlobalEventExecutor; /*** * 存储整个工程的全局配置 */ public class NettyConfig { /*** * 存储每一个客户端接入进来时的Channel对象 */ public static ChannelGroup group = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE); }

2.接收/处理/响应客户端websocket请求的核心业务处理类

package com.research.netty.WebSocket; import java.util.Date; 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.SimpleChannelInboundHandler; import io.netty.channel.group.ChannelGroup; import io.netty.channel.group.ChannelMatcher; import io.netty.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpRequest; import io.netty.handler.codec.http.HttpResponseStatus; 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; /** * 接收/处理/响应客户端websocket请求的核心业务处理类 */ public class MyWebSocketHandler extends SimpleChannelInboundHandler<Object> { //握手 private WebSocketServerHandshaker handshaker; private static final String WEB_SOCKET_URL = "ws://localhost:8888/websocket"; //客户端与服务端创建连接的时候调用 @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { NettyConfig.group.add(ctx.channel()); System.out.println("客户端与服务端连接开启..."); } //客户端与服务端断开连接的时候调用 @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { NettyConfig.group.remove(ctx.channel()); System.out.println("客户端与服务端连接关闭..."); } //服务端接收客户端发送过来的数据结束之后调用 @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } //工程出现异常的时候调用 @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); } //服务端处理客户端websocket请求的核心方法 @Override protected void messageReceived(ChannelHandlerContext context, Object msg) throws Exception { //处理客户端向服务端发起http握手请求的业务 if (msg instanceof FullHttpRequest) { handHttpRequest(context, (FullHttpRequest) msg); } else if (msg instanceof WebSocketFrame) { //处理websocket连接业务 handWebsocketFrame(context, (WebSocketFrame) msg); } } /** * 处理客户端与服务端之前的websocket业务 * * @param ctx * @param frame */ private void handWebsocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) { //判断是否是关闭websocket的指令 if (frame instanceof CloseWebSocketFrame) { handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain()); } //判断是否是ping消息 if (frame instanceof PingWebSocketFrame) { ctx.channel().write(new PongWebSocketFrame(frame.content().retain())); return; } //判断是否是二进制消息，如果是二进制消息，抛出异常（我们这个例子不支持二进制消息） if (!(frame instanceof TextWebSocketFrame)) { System.out.println("目前我们不支持二进制消息"); throw new RuntimeException("【" + this.getClass().getName() + "】不支持消息"); } //返回应答消息 //获取客户端向服务端发送的消息 String request = ((TextWebSocketFrame) frame).text(); System.out.println("服务端收到客户端的消息====>>>" + request); TextWebSocketFrame tws = new TextWebSocketFrame(new Date().toString() + ctx.channel().id() + " ===>>> " + request); //群发，服务端向每个连接上来的客户端群发消息 NettyConfig.group.writeAndFlush(tws); } /** * 处理客户端向服务端发起http握手请求的业务 * * @param ctx * @param req */ private void handHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) { if (!req.getDecoderResult().isSuccess() || !("websocket".equals(req.headers().get("Upgrade")))) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.BAD_REQUEST)); return; } WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory( WEB_SOCKET_URL, null, false); handshaker = wsFactory.newHandshaker(req); if (handshaker == null) { WebSocketServerHandshakerFactory.sendUnsupportedWebSocketVersionResponse(ctx.channel()); } else { handshaker.handshake(ctx.channel(), req); } } /** * 服务端向客户端响应消息 * * @param ctx * @param req * @param res */ private void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, DefaultFullHttpResponse res) { if (res.getStatus().code() != 200) { ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8); res.content().writeBytes(buf); buf.release(); } //服务端向客户端发送数据 ChannelFuture f = ctx.channel().writeAndFlush(res); if (res.getStatus().code() != 200) { f.addListener(ChannelFutureListener.CLOSE); } } }

3.初始化连接时候的各个组件

package com.research.netty.WebSocket; import io.netty.channel.ChannelInitializer; import io.netty.channel.socket.SocketChannel; import io.netty.handler.codec.http.HttpObjectAggregator; import io.netty.handler.codec.http.HttpServerCodec; import io.netty.handler.stream.ChunkedWriteHandler; /** * 初始化连接时候的各个组件 */ public class MyWebSocketChannelHandler extends ChannelInitializer<SocketChannel> { @Override protected void initChannel(SocketChannel e) throws Exception { e.pipeline().addLast("http-codec", new HttpServerCodec()); e.pipeline().addLast("aggregator", new HttpObjectAggregator(65536)); e.pipeline().addLast("http-chunked", new ChunkedWriteHandler()); e.pipeline().addLast("handler", new MyWebSocketHandler()); } }

4.程序的入口，负责启动应用

package com.research.netty.WebSocket; import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.Channel; import io.netty.channel.EventLoopGroup; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.nio.NioServerSocketChannel; /** * 程序的入口，负责启动应用 */ public class Main { public static void main(String[] args) { //配置服务端NIO线程组 EventLoopGroup bossGroup = new NioEventLoopGroup(); EventLoopGroup workGroup = new NioEventLoopGroup(); try { ServerBootstrap b = new ServerBootstrap(); b.group(bossGroup, workGroup); b.channel(NioServerSocketChannel.class); b.childHandler(new MyWebSocketChannelHandler()); System.out.println("服务端开启等待客户端连接...."); Channel ch = b.bind(8888).sync().channel(); ch.closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); }finally{ //优雅的退出程序 bossGroup.shutdownGracefully(); workGroup.shutdownGracefully(); } } }

5.html

<html> <head> <meta http-equiv="Content-Type" content="text/html; charset = utf-8"/> <title>WebSocket客户端</title> <script type="text/javascript"> var socket; if(!window.WebSocket){ window.WebSocket = window.MozWebSocket; } if(window.WebSocket){ socket = new WebSocket("ws://localhost:8888/websocket"); socket.onmessage = function(event){ var ta = document.getElementById('responseContent'); ta.value += event.data + "\r\n"; }; socket.onopen = function(event){ var ta = document.getElementById('responseContent'); ta.value = "你当前的浏览器支持WebSocket,请进行后续操作\r\n"; }; socket.onclose = function(event){ var ta = document.getElementById('responseContent'); ta.value = ""; ta.value = "WebSocket连接已经关闭\r\n"; }; }else{ alert("您的浏览器不支持WebSocket"); } window.onbeforeunload = function(){ ws.close(); } 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> </head> <body> <form onSubmit="return false;"> <input type = "text" name = "message" value = ""/> <br/><br/> <input type = "button" value = "发送WebSocket请求消息" onClick = "send(this.form.message.value)"/> <hr color="red"/> <h2>客户端接收到服务端返回的应答消息</h2> <textarea id = "responseContent" style = "width:1024px; height:300px"></textarea> </form> </body> </html>

 

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