現在網上網站為了實現推送基本都采用輪詢的方式，比較新的輪詢技術是comet，采用ajax，但是還是得發送請求，為了解決html效率低下的問題，html5定義了websocket協議。

服務端代碼：

import java.util.concurrent.TimeUnit;import org.apache.activemq.util.TimeUtils;import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.Channel; import io.netty.channel.ChannelInitializer; import io.netty.channel.EventLoopGroup; 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.HttpObjectAggregator; import io.netty.handler.codec.http.HttpServerCodec; import io.netty.handler.logging.LogLevel; import io.netty.handler.logging.LoggingHandler; import io.netty.handler.stream.ChunkedWriteHandler;public class WebSocketServer {public void bind(int port) throws Exception {EventLoopGroup parentGroup = new NioEventLoopGroup();EventLoopGroup childGroup = new NioEventLoopGroup();try {ServerBootstrap b = new ServerBootstrap();b.group(parentGroup, childGroup).channel(NioServerSocketChannel.class).handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch)throws Exception {ch.pipeline().addLast("http-codec",new HttpServerCodec());ch.pipeline().addLast("aggregator",new HttpObjectAggregator(65536));ch.pipeline().addLast("http-chunked",new ChunkedWriteHandler());ch.pipeline().addLast("handler",new WebSocketServerHandler());}});Channel f = b.bind(port).sync().channel();f.closeFuture().sync();} finally{parentGroup.shutdownGracefully();childGroup.shutdownGracefully();}}/*** @param args*/public static void main(String[] args) throws Exception{// TODO Auto-generated method stubnew WebSocketServer().bind(8080);}}

handler

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.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpRequest; import io.netty.handler.codec.http.FullHttpResponse; import io.netty.handler.codec.http.HttpHeaderUtil; 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;import java.util.Date;public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {private WebSocketServerHandshaker handshaker;@Overrideprotected void messageReceived(ChannelHandlerContext ctx, Object msg)throws Exception {// TODO Auto-generated method stubif(msg instanceof FullHttpRequest){handleHttpRequest(ctx, (FullHttpRequest)msg);}else if(msg instanceof WebSocketFrame){handleWebSocketFrame(ctx, (WebSocketFrame) msg);}}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) throws Exception {ctx.flush();}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)throws Exception {cause.printStackTrace();ctx.close();}private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) throws Exception{System.out.println("handleHttpRequest");if(!req.decoderResult().isSuccess() || !"websocket".equals(req.headers().get("Upgrade"))){sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.BAD_REQUEST));return;}WebSocketServerHandshakerFactory factory = new WebSocketServerHandshakerFactory("ws://localhost:8080/websocket", null, false);handshaker = factory.newHandshaker(req);if(handshaker == null){WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());}else{handshaker.handshake(ctx.channel(), req);}}private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame){System.out.println("handleWebSocketFrame");if(frame instanceof CloseWebSocketFrame){handshaker.close(ctx.channel(), (CloseWebSocketFrame)frame.retain());return;}if(frame instanceof PingWebSocketFrame){ctx.channel().write(new PongWebSocketFrame(frame.content().retain()));return;}if(!(frame instanceof TextWebSocketFrame)){throw new UnsupportedOperationException(String.format("%s frame types not support", frame.getClass().getName()));}String req = ((TextWebSocketFrame) frame).text();System.out.println(String.format("%s received %s", ctx.channel(), req));for(int i = 0; i < 10; i++){ctx.channel().writeAndFlush(new TextWebSocketFrame(req+",歡迎使用Netty Websocket服務，現在時刻：" + new Date().toString()));try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}}private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) throws Exception{if(res.status().code() != 200){ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(),CharsetUtil.UTF_8);res.content().writeBytes(buf);buf.release();HttpHeaderUtil.setContentLength(res, res.content().readableBytes());}ChannelFuture f = ctx.channel().writeAndFlush(res);if(!HttpHeaderUtil.isKeepAlive(req) || res.status().code() != 200){f.addListener(ChannelFutureListener.CLOSE);}}}

html調用：

<html><head><meta charset="utf-8">Netty Socket時間服務器</head><body><script type="text/javascript">var socket;if(!window.WebSocket){window.WebSocket = window.MozWebSocket;}if(window.WebSocket){socket = new WebSocket("ws://localhost:8080/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 ="打開websocket服務正常，瀏覽器支持websocket"; };socket.onclose = function(event){var ta = document.getElementById("responseText");ta.value = "";ta.value = "websocket關閉";};}else{alert("抱歉，瀏覽器不支持websocket");}function send(msg){if(socket.readyState = WebSocket.OPEN){socket.send(msg);}else{alert("沒有建立連接");}}</script><form><input type="text" name="message" value="Netty最佳"/><input type="button" value="發送websocket請求信息" onclick="send(this.form.message.value)"/><hr color="blue"><textarea id="responseText" style="width:500px;height:300px"></textarea></form></body> </html>

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轉載于:https://www.cnblogs.com/momofeng/p/5482827.html

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