WebSocket +Jetty+jQuery 实现服务器消息推送例子

服务器servlet代码

package flowersinthesand.example;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Queue;
import java.util.UUID;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.LinkedBlockingQueue;

import javax.servlet.AsyncContext;
import javax.servlet.AsyncEvent;
import javax.servlet.AsyncListener;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.util.UrlEncoded;
import org.eclipse.jetty.websocket.WebSocket;
import org.eclipse.jetty.websocket.WebSocketServlet;

import com.google.gson.Gson;

@WebServlet(urlPatterns = "/chat", asyncSupported = true)
public class ChatServlet extends WebSocketServlet {

	private static final long serialVersionUID = 4805728426990609124L;

	private Map<String, AsyncContext> asyncContexts = new ConcurrentHashMap<String, AsyncContext>();
	private Queue<ChatWebSocket> webSockets = new ConcurrentLinkedQueue<ChatWebSocket>();
	private BlockingQueue<String> messages = new LinkedBlockingQueue<String>();
	private Thread notifier = new Thread(new Runnable() {
		public void run() {
			while (true) {
				try {
					// Waits until a message arrives
					String message = messages.take();

					// Sends the message to all the AsyncContext's response
					for (AsyncContext asyncContext : asyncContexts.values()) {
						try {
							sendMessage(asyncContext.getResponse().getWriter(), message);
						} catch (Exception e) {
							asyncContexts.values().remove(asyncContext);
						}
					}

					// Sends the message to all the WebSocket's connection
					for (ChatWebSocket webSocket : webSockets) {
						try {
							webSocket.connection.sendMessage(message);
						} catch (Exception e) {
							webSockets.remove(webSocket);
						}
					}
				} catch (InterruptedException e) {
					break;
				}
			}
		}
	});

	private void sendMessage(PrintWriter writer, String message) throws IOException {
		// default message format is message-size ; message-data ;
		writer.print(message.length());
		writer.print(";");
		writer.print(message);
		writer.print(";");
		writer.flush();
	}

	@Override
	public void init(ServletConfig config) throws ServletException {
		super.init(config);
		notifier.start();
	}

	// GET method is used to establish a stream connection
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		// Content-Type header
		response.setContentType("text/plain");
		response.setCharacterEncoding("utf-8");

		// Access-Control-Allow-Origin header
		response.setHeader("Access-Control-Allow-Origin", "*");

		PrintWriter writer = response.getWriter();

		// Id
		final String id = UUID.randomUUID().toString();
		writer.print(id);
		writer.print(';');

		// Padding
		for (int i = 0; i < 1024; i++) {
			writer.print(' ');
		}
		writer.print(';');
		writer.flush();

		final AsyncContext ac = request.startAsync();
		ac.addListener(new AsyncListener() {
			public void onComplete(AsyncEvent event) throws IOException {
				asyncContexts.remove(id);
			}

			public void onTimeout(AsyncEvent event) throws IOException {
				asyncContexts.remove(id);
			}

			public void onError(AsyncEvent event) throws IOException {
				asyncContexts.remove(id);
			}

			public void onStartAsync(AsyncEvent event) throws IOException {

			}
		});
		asyncContexts.put(id, ac);
	}

	// POST method is used to communicate with the server
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");

		AsyncContext ac = asyncContexts.get(request.getParameter("metadata.id"));
		if (ac == null) {
			return;
		}

		// close-request
		if ("close".equals(request.getParameter("metadata.type"))) {
			ac.complete();
			return;
		}

		// send-request
		Map<String, String> data = new LinkedHashMap<String, String>();
		data.put("username", request.getParameter("username"));
		data.put("message", request.getParameter("message"));

		try {
			messages.put(new Gson().toJson(data));
		} catch (InterruptedException e) {
			throw new IOException(e);
		}
	}

	@Override
	public WebSocket doWebSocketConnect(HttpServletRequest request, String protocol) {
		return new ChatWebSocket();
	}

	class ChatWebSocket implements WebSocket.OnTextMessage {

		Connection connection;

		@Override
		public void onOpen(Connection connection) {
			this.connection = connection;
			webSockets.add(this);
		}

		@Override
		public void onClose(int closeCode, String message) {
			webSockets.remove(this);
		}

		@Override
		public void onMessage(String queryString) {
			// Parses query string
			UrlEncoded parameters = new UrlEncoded(queryString);

			Map<String, String> data = new LinkedHashMap<String, String>();
			data.put("username", parameters.getString("username"));
			data.put("message", parameters.getString("message"));

			try {
				messages.put(new Gson().toJson(data));
			} catch (InterruptedException e) {
				throw new RuntimeException(e);
			}
		}

	}

	@Override
	public void destroy() {
		messages.clear();
		webSockets.clear();
		asyncContexts.clear();
		notifier.interrupt();
	}

}

html代码

<!DOCTYPE html>
<html>
	<head>
		<title>Chat - Jetty 8</title>
		<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
		<script type="text/javascript" src="jquery-1.5.0.js"></script>
		<script type="text/javascript" src="jquery.stream-1.2.js"></script>
		<script type="text/javascript">
		$.stream.setup({enableXDR: true});
		
		var chat = {
			lastUsername: "Donghwan Kim",
			username: $.trim(window.prompt("Username?")) || "Anonymous" + $(window).width()
		};
		
		$(function() {
			$.stream("chat", {
				dataType: "json",
				context: $("#content")[0],
				open: function(event, stream) {
					$("#editor .message").removeAttr("disabled").focus();
					stream.send({username: chat.username, message: "Hello"});
				},
				message: function(event) {
					if (chat.lastUsername !== event.data.username) {
						$("<p />").addClass("user").text(chat.lastUsername = event.data.username).appendTo(this);
					}
					
					$("<p />").addClass("message").text(event.data.message).appendTo(this);
					this.scrollTop = this.scrollHeight;
				},
				error: function() {
					$("#editor .message").attr("disabled", "disabled");
				},
				close: function() {
					$("#editor .message").attr("disabled", "disabled");
				}
			});
			
			$("#editor .user").text(chat.username);
			$("#editor .message").keyup(function(event) {
				if (event.which === 13 && $.trim(this.value)) {
					$.stream().send({username: chat.username, message: this.value});
					this.value = "";
				}
			});
			
			$(window).resize(function() {
				var content = $("#content").height($(window).height() - $("#editor").outerHeight(true) - 15)[0];
				content.scrollTop = content.scrollHeight;
			}).resize();
		});
		</script>
		<style>
		body {padding: 0; margin: 0; min-width: 320px; font-family: 'Trebuchet MS','Malgun Gothic',Verdana,Helvetica,Arial,sans-serif; font-size: 62.5%; color: #333333}
		.content {height: 100%; overflow-y: auto; padding: 14px 15px 0 25px;}
		.content p {margin: 0; padding: 0;}
		.content .user {font-size: 1.8em; color: #3e3e3e; font-weight: bold; letter-spacing: -1px; margin-top: 0.5em;}
		.content .message {font-size: 1.3em; color: #444444; line-height: 1.7em; word-wrap: break-word;}
		.editor {margin: 0 25px 15px 25px;}
		.editor .user {font-size: 1.5em; display: inline-block; margin: 1em;}
		.editor input {font-family: 'Trebuchet MS','Malgun Gothic',Verdana,Helvetica,Arial,sans-serif;}
		.editor .message {width: 100%; height: 28px; line-height: 28px; border: medium none; border-color: #E5E5E5 #DBDBDB #D2D2D2; border-style: solid; border-width: 1px;}
		</style>
	</head>
	<body>
		<div id="content" class="content">
			<p class="user"><span>Donghwan Kim</span></p>
			<p class="message">Welcome to jQuery Stream!</p>
		</div>
		<div id="editor" class="editor">
			<p class="user"></p>
			<form action="#" οnsubmit="return false;">
				<input class="message" type="text" disabled="disabled" />
			</form>
		</div>
	</body>
</html>

另需要

jquery-1.5.0.js

jquery.stream-1.2.js

参考 https://code.google.com/p/jquery-stream/

压力测试插件

https://github.com/kawasima/jmeter-websocket