Web Socket入门

最近对html5产生了兴趣，所以花了点心思在这方面，基于JBoss Netty写了个简单的web socket应用，主要拷贝了Netty的官方范例代码，如果想深入了解的话，最好还是好好看看Java NIO及Netty。

服务器端代码：
1、创建一个简单的管道实现：

package org.penguin.study.nettty.http.websocket;

import static org.jboss.netty.channel.Channels.pipeline;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.handler.codec.http.HttpChunkAggregator;
import org.jboss.netty.handler.codec.http.HttpRequestDecoder;
import org.jboss.netty.handler.codec.http.HttpResponseEncoder;

public class WebSocketServerPipelineFactory implements ChannelPipelineFactory {
	public ChannelPipeline getPipeline() throws Exception {
		// Create a default pipeline implementation.
		ChannelPipeline pipeline = pipeline();
		pipeline.addLast("decoder", new HttpRequestDecoder());
		pipeline.addLast("aggregator", new HttpChunkAggregator(65536));
		pipeline.addLast("encoder", new HttpResponseEncoder());
		pipeline.addLast("handler", new WebSocketServerHandler());
		return pipeline;
	}
}

 2、 请求处理，可是最重要的一部分，核心代码尽在于此：

package org.penguin.study.nettty.http.websocket;

import static org.jboss.netty.handler.codec.http.HttpHeaders.*;
import static org.jboss.netty.handler.codec.http.HttpHeaders.Names.*;
import static org.jboss.netty.handler.codec.http.HttpHeaders.Values.*;
import static org.jboss.netty.handler.codec.http.HttpMethod.*;
import static org.jboss.netty.handler.codec.http.HttpResponseStatus.*;
import static org.jboss.netty.handler.codec.http.HttpVersion.*;

import java.security.MessageDigest;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.handler.codec.http.DefaultHttpResponse;
import org.jboss.netty.handler.codec.http.HttpHeaders;
import org.jboss.netty.handler.codec.http.HttpRequest;
import org.jboss.netty.handler.codec.http.HttpResponse;
import org.jboss.netty.handler.codec.http.HttpResponseStatus;
import org.jboss.netty.handler.codec.http.HttpHeaders.Names;
import org.jboss.netty.handler.codec.http.HttpHeaders.Values;
import org.jboss.netty.handler.codec.http.websocket.DefaultWebSocketFrame;
import org.jboss.netty.handler.codec.http.websocket.WebSocketFrame;
import org.jboss.netty.handler.codec.http.websocket.WebSocketFrameDecoder;
import org.jboss.netty.handler.codec.http.websocket.WebSocketFrameEncoder;
import org.jboss.netty.util.CharsetUtil;

public class WebSocketServerHandler extends SimpleChannelUpstreamHandler {

	private static final String WEBSOCKET_PATH = "/websocket";

	@Override
	public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
		Object msg = e.getMessage();
		if (msg instanceof HttpRequest) {
			handleHttpRequest(ctx, (HttpRequest) msg);
		} else if (msg instanceof WebSocketFrame) {
			handleWebSocketFrame(ctx, (WebSocketFrame) msg);
		}
	}

	private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req) throws Exception {
		// Serve the WebSocket handshake request.
		if (req.getUri().equals(WEBSOCKET_PATH) && Values.UPGRADE.equalsIgnoreCase(req.getHeader(CONNECTION))
				&& WEBSOCKET.equalsIgnoreCase(req.getHeader(Names.UPGRADE))) {

			// Create the WebSocket handshake response.
			HttpResponse res = new DefaultHttpResponse(HTTP_1_1, new HttpResponseStatus(101, "Web Socket Protocol Handshake"));
			res.addHeader(Names.UPGRADE, WEBSOCKET);
			res.addHeader(CONNECTION, Values.UPGRADE);

			// Fill in the headers and contents depending on handshake method.
			if (req.containsHeader(SEC_WEBSOCKET_KEY1) && req.containsHeader(SEC_WEBSOCKET_KEY2)) {
				// New handshake method with a challenge:
				res.addHeader(SEC_WEBSOCKET_ORIGIN, req.getHeader(ORIGIN));
				res.addHeader(SEC_WEBSOCKET_LOCATION, getWebSocketLocation(req));
				String protocol = req.getHeader(SEC_WEBSOCKET_PROTOCOL);
				if (protocol != null) {
					res.addHeader(SEC_WEBSOCKET_PROTOCOL, protocol);
				}

				// Calculate the answer of the challenge.
				String key1 = req.getHeader(SEC_WEBSOCKET_KEY1);
				String key2 = req.getHeader(SEC_WEBSOCKET_KEY2);
				int a = (int) (Long.parseLong(key1.replaceAll("[^0-9]", "")) / key1.replaceAll("[^ ]", "").length());
				int b = (int) (Long.parseLong(key2.replaceAll("[^0-9]", "")) / key2.replaceAll("[^ ]", "").length());
				long c = req.getContent().readLong();
				ChannelBuffer input = ChannelBuffers.buffer(16);
				input.writeInt(a);
				input.writeInt(b);
				input.writeLong(c);
				
				ChannelBuffer output = ChannelBuffers.wrappedBuffer(MessageDigest.getInstance("MD5").digest(	input.array()));
				res.setContent(output);
			} else {				
				res.addHeader(WEBSOCKET_ORIGIN, req.getHeader(ORIGIN));
				res.addHeader(WEBSOCKET_LOCATION, getWebSocketLocation(req));
				String protocol = req.getHeader(WEBSOCKET_PROTOCOL);
				if (protocol != null) {
					res.addHeader(WEBSOCKET_PROTOCOL, protocol);
				}
			}

			// Upgrade the connection and send the handshake response.
			ChannelPipeline p = ctx.getChannel().getPipeline();
			p.remove("aggregator");
			p.replace("decoder", "wsdecoder", new WebSocketFrameDecoder());

			ctx.getChannel().write(res);

			p.replace("encoder", "wsencoder", new WebSocketFrameEncoder());
			return;
		}

		// Send an error page otherwise.
		sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1, FORBIDDEN));
	}
	private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
		// 发送消息回执
                                ctx.getChannel().write(new DefaultWebSocketFrame("动拐动拐，我是动爻，消息已收到：" + frame.getTextData()));
	}

	private void sendHttpResponse(ChannelHandlerContext ctx, HttpRequest req, HttpResponse res) {
		// Generate an error page if response status code is not OK (200).
		if (res.getStatus().getCode() != 200) {
			res.setContent(ChannelBuffers.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8));
			setContentLength(res, res.getContent().readableBytes());
		}
		// Send the response and close the connection if necessary.
		ChannelFuture f = ctx.getChannel().write(res);
		if (!isKeepAlive(req) || res.getStatus().getCode() != 200) {
			f.addListener(ChannelFutureListener.CLOSE);
		}
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
		System.err.println("出现错误：" + e.getCause().getMessage());
		e.getChannel().close();
	}

	private String getWebSocketLocation(HttpRequest req) {
		return "ws://" + req.getHeader(HttpHeaders.Names.HOST) + WEBSOCKET_PATH;
	}
}

 3、服务器代码：

package org.penguin.study.nettty.http.websocket;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;

public class WebSocketServer {
	public static void main(String[] args) {
		// Configure the server.
		ServerBootstrap bootstrap = new ServerBootstrap(new NioServerSocketChannelFactory(
				Executors.newCachedThreadPool(), Executors.newCachedThreadPool()));

		// Set up the event pipeline factory.
		bootstrap.setPipelineFactory(new WebSocketServerPipelineFactory());

		// Bind and start to accept incoming connections.
		bootstrap.bind(new InetSocketAddress(8888));
	}
}

 4、测试的浏览器代码，在Google Chrome下测试正常运行，IE、Firefox、360目前不支持Web Socket。

写道

<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>Web Socket范例</title>
<script type="text/javascript">
var socket;
if (window.WebSocket) {
socket = new WebSocket("ws://WebSocket服务器地址:8888/websocket");
socket.onmessage = function(event) { alert(event.data); };
socket.onopen = function(event) { alert("Web Socket成功链接！"); };
socket.onclose = function(event) { alert("Web Socket已被关闭！"); };
} else {
alert("对不起，您的浏览器不支持Web Socket，目前建议使用新版的Chrome浏览器！");
}

function send(message) {
if (!window.WebSocket) { return; }
if (socket.readyState == WebSocket.OPEN) {
socket.send(message);
} else {
alert("没有打开Socket，请检查网络及服务器是否正常运行！");
}
}
</script>

</head>

<body>
<form onsubmit="return false;">
<input type="text" name="message" value="动爻动爻，我是动拐"/><input type="button" value="发送" onclick="send(this.form.message.value)" />
</form>

</body>
</html>