netty实现websocket

现在网上网站为了实现推送基本都采用轮询的方式，比较新的轮询技术是comet，采用ajax，但是还是得发送请求，为了解决html效率低下的问题，html5定义了websocket协议。

服务端代码：

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>() {

@Override
protected 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 stub
new 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;

@Override
protected void messageReceived(ChannelHandlerContext ctx, Object msg)
throws Exception {
// TODO Auto-generated method stub
if(msg instanceof FullHttpRequest){
handleHttpRequest(ctx, (FullHttpRequest)msg);
}else if(msg instanceof WebSocketFrame){
handleWebSocketFrame(ctx, (WebSocketFrame) msg);
}
}

@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}

@Override
public 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+",欢迎使用Netty Websocket服务，现在时刻：" + 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调用：

<html>
<head>
<meta charset="utf-8">
Netty Socket时间服务器
</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，浏览器不支持websocket");
}

function send(msg){
if(socket.readyState = WebSocket.OPEN){
socket.send(msg);
}else{
alert("没有建立连接");
}
}
</script>

<form>
<input type="text" name="message" value="Netty最佳"/>
<input type="button" value="发送websocket请求信息" onclick="send(this.form.message.value)"/>
<hr color="blue">
<textarea id="responseText" style="width:500px;height:300px"></textarea>

</form>
</body>
</html>