pushlet单播与多播

近期要弄一个消息推送的功能，在网上找了非常多的关于pushlet的文章，尽管写的都非常具体，可是本人看了以后却总认为是模棱两可···不知道怎样下手，终于參考了这些文章中的一些内容，并结合官网的源码。做了自己的改动。

第一部分  改动的地方

首先改动了nl.justobjects.pushlet.core.Session，添加了even字段，添加了getEvent（）方法，同一时候改动了create（）方法，改动例如以下：

// Copyright (c) 2000 Just Objects B.V. <just@justobjects.nl>
// Distributable under LGPL license. See terms of license at gnu.org.

package nl.justobjects.pushlet.core;

import nl.justobjects.pushlet.util.Log;
import nl.justobjects.pushlet.util.PushletException;

/**
 * Represents client pushlet session state.
 *
 * @author Just van den Broecke - Just Objects &copy;
 * @version $Id: Session.java,v 1.8 2007/11/23 14:33:07 justb Exp $
 */
public class Session implements Protocol, ConfigDefs {
	private Controller controller;
	private Subscriber subscriber;
	/** 添加了even字段 */
	private Event event;

	private String userAgent;
	private long LEASE_TIME_MILLIS = Config
			.getLongProperty(SESSION_TIMEOUT_MINS) * 60 * 1000;
	private volatile long timeToLive = LEASE_TIME_MILLIS;

	public static String[] FORCED_PULL_AGENTS = Config.getProperty(
			LISTEN_FORCE_PULL_AGENTS).split(",");

	private String address = "unknown";
	private String format = FORMAT_XML;

	private String id;

	/**
	 * Protected constructor as we create through factory method.
	 */
	protected Session() {
	}

	/**
	 * Create instance through factory method.
	 *
	 * @param anId
	 *            a session id
	 * @return a Session object (or derived)
	 * @throws PushletException
	 *             exception, usually misconfiguration
	 */

	/** 改动前的create方法 */
	// public static Session create(String anId) throws PushletException {
	// Session session;
	// try {
	// session = (Session) Config.getClass(SESSION_CLASS,
	// "nl.justobjects.pushlet.core.Session").newInstance();
	// } catch (Throwable t) {
	// throw new PushletException(
	// "Cannot instantiate Session from config", t);
	// }
	//
	// // Init session
	// session.id = anId;
	// session.controller = Controller.create(session);
	// session.subscriber = Subscriber.create(session);
	// return session;
	// }

	public static Session create(String anId, Event anEvent)
			throws PushletException {
		Session session;
		try {
			session = (Session) Config.getClass(SESSION_CLASS,
					"nl.justobjects.pushlet.core.Session").newInstance();
		} catch (Throwable t) {
			throw new PushletException(
					"Cannot instantiate Session from config", t);
		}

		// Init session
		session.id = anId;
		session.controller = Controller.create(session);
		session.subscriber = Subscriber.create(session);
		session.event = anEvent;
		return session;
	}

	/**
	 * 添加了getEVent方法
	 */
	public Event getEvent() {
		return event;
	}

	/**
	 * Return (remote) Subscriber client's IP address.
	 */
	public String getAddress() {
		return address;
	}

	/**
	 * Return command controller.
	 */
	public Controller getController() {
		return controller;
	}

	/**
	 * Return Event format to send to client.
	 */
	public String getFormat() {
		return format;
	}

	/**
	 * Return (remote) Subscriber client's unique id.
	 */
	public String getId() {
		return id;
	}

	/**
	 * Return subscriber.
	 */
	public Subscriber getSubscriber() {
		return subscriber;
	}

	/**
	 * Return remote HTTP User-Agent.
	 */
	public String getUserAgent() {
		return userAgent;
	}

	/**
	 * Set address.
	 */
	protected void setAddress(String anAddress) {
		address = anAddress;
	}

	/**
	 * Set event format to encode.
	 */
	protected void setFormat(String aFormat) {
		format = aFormat;
	}

	/**
	 * Set client HTTP UserAgent.
	 */
	public void setUserAgent(String aUserAgent) {
		userAgent = aUserAgent;
	}

	/**
	 * Decrease time to live.
	 */
	public void age(long aDeltaMillis) {
		timeToLive -= aDeltaMillis;
	}

	/**
	 * Has session timed out?
	 */
	public boolean isExpired() {
		return timeToLive <= 0;
	}

	/**
	 * Keep alive by resetting TTL.
	 */
	public void kick() {
		timeToLive = LEASE_TIME_MILLIS;
	}

	public void start() {
		SessionManager.getInstance().addSession(this);
	}

	public void stop() {
		subscriber.stop();
		SessionManager.getInstance().removeSession(this);
	}

	/**
	 * Info.
	 */
	public void info(String s) {
		Log.info("S-" + this + ": " + s);
	}

	/**
	 * Exceptional print util.
	 */
	public void warn(String s) {
		Log.warn("S-" + this + ": " + s);
	}

	/**
	 * Exceptional print util.
	 */
	public void debug(String s) {
		Log.debug("S-" + this + ": " + s);
	}

	public String toString() {
		return getAddress() + "[" + getId() + "]";
	}
}

/*
 * $Log: Session.java,v $ Revision 1.8 2007/11/23 14:33:07 justb core classes
 * now configurable through factory
 *
 * Revision 1.7 2005/02/28 15:58:05 justb added SimpleListener example
 *
 * Revision 1.6 2005/02/28 12:45:59 justb introduced Command class
 *
 * Revision 1.5 2005/02/28 09:14:55 justb sessmgr/dispatcher factory/singleton
 * support
 *
 * Revision 1.4 2005/02/25 15:13:01 justb session id generation more robust
 *
 * Revision 1.3 2005/02/21 16:59:08 justb SessionManager and session lease
 * introduced
 *
 * Revision 1.2 2005/02/21 12:32:28 justb fixed publish event in Controller
 *
 * Revision 1.1 2005/02/21 11:50:46 justb ohase1 of refactoring Subscriber into
 * Session/Controller/Subscriber
 */

然后改动了nl.justobjects.pushlet.core.SessionManager，改动了createSession（）方法：

// Copyright (c) 2000 Just Objects B.V. <just@justobjects.nl>
// Distributable under LGPL license. See terms of license at gnu.org.

package nl.justobjects.pushlet.core;

import nl.justobjects.pushlet.util.Log;
import nl.justobjects.pushlet.util.PushletException;
import nl.justobjects.pushlet.util.Rand;
import nl.justobjects.pushlet.util.Sys;

import java.rmi.server.UID;
import java.util.*;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

/**
 * Manages lifecycle of Sessions.
 *
 * @author Just van den Broecke - Just Objects &copy;
 * @version $Id: SessionManager.java,v 1.12 2007/12/04 13:55:53 justb Exp $
 */
public class SessionManager implements ConfigDefs {

	/**
	 * Singleton pattern: single instance.
	 */
	private static SessionManager instance;

	static {
		// Singleton + factory pattern: create single instance
		// from configured class name
		try {
			instance = (SessionManager) Config.getClass(SESSION_MANAGER_CLASS,
					"nl.justobjects.pushlet.core.SessionManager").newInstance();
			Log.info("SessionManager created className=" + instance.getClass());
		} catch (Throwable t) {
			Log.fatal("Cannot instantiate SessionManager from config", t);
		}
	}

	/**
	 * Timer to schedule session leasing TimerTasks.
	 */
	private Timer timer;
	private final long TIMER_INTERVAL_MILLIS = 60000;

	/**
	 * Map of active sessions, keyed by their id, all access is through mutex.
	 */
	private Map sessions = new HashMap(13);

	/**
	 * Cache of Sessions for iteration and to allow concurrent modification.
	 */
	private Session[] sessionCache = new Session[0];

	/**
	 * State of SessionCache, becomes true whenever sessionCache out of sync
	 * with sessions Map.
	 */
	private boolean sessionCacheDirty = false;

	/**
	 * Lock for any operation on Sessions (Session Map and/or -cache).
	 */
	private final Object mutex = new Object();

	/**
	 * Singleton pattern: protected constructor needed for derived classes.
	 */
	protected SessionManager() {
	}

	/**
	 * Visitor pattern implementation for Session iteration.
	 * <p/>
	 * This method can be used to iterate over all Sessions in a threadsafe way.
	 * See Dispatcher.multicast and broadcast methods for examples.
	 *
	 * @param visitor
	 *            the object that should implement method parm
	 * @param method
	 *            the method to be called from visitor
	 * @param args
	 *            arguments to be passed in visit method, args[0] will always be
	 *            Session object
	 */
	public void apply(Object visitor, Method method, Object[] args) {

		synchronized (mutex) {

			// Refresh Session cache if required
			// We use a cache for two reasons:
			// 1. to prevent concurrent modification from within visitor method
			// 2. some optimization (vs setting up Iterator for each apply()
			if (sessionCacheDirty) {
				// Clear out existing cache
				for (int i = 0; i < sessionCache.length; i++) {
					sessionCache[i] = null;
				}

				// Refill cache and update state
				sessionCache = (Session[]) sessions.values().toArray(
						sessionCache);
				sessionCacheDirty = false;
			}

			// Valid session cache: loop and call supplied Visitor method
			Session nextSession;
			for (int i = 0; i < sessionCache.length; i++) {
				nextSession = sessionCache[i];

				// Session cache may not be entirely filled
				if (nextSession == null) {
					break;
				}

				try {
					// First argument is always a Session object
					args[0] = nextSession;

					// Use Java reflection to call the method passed by the
					// Visitor
					method.invoke(visitor, args);
				} catch (IllegalAccessException e) {
					Log.warn("apply: illegal method access: ", e);
				} catch (InvocationTargetException e) {
					Log.warn("apply: method invoke: ", e);
				}
			}
		}
	}

	/**
	 * Create new Session (but add later).
	 */

	/**
	 * public Session createSession(Event anEvent) throws PushletException {
	 * return Session.create(createSessionId());}
	 *
	 *
	 * 这是原来的createSession方法，能够看到。尽管有anEvent參数··可是却没有在createSession的时候使用
	 */

	public Session createSession(Event anEvent) throws PushletException {
		// Trivial
		return Session.create(createSessionId(), anEvent);
	}

	/**
	 * Singleton pattern: get single instance.
	 */
	public static SessionManager getInstance() {
		return instance;
	}

	/**
	 * Get Session by session id.
	 */
	public Session getSession(String anId) {
		synchronized (mutex) {
			return (Session) sessions.get(anId);
		}
	}

	/**
	 * Get copy of listening Sessions.
	 */
	public Session[] getSessions() {
		synchronized (mutex) {
			return (Session[]) sessions.values().toArray(new Session[0]);
		}
	}

	/**
	 * Get number of listening Sessions.
	 */
	public int getSessionCount() {
		synchronized (mutex) {
			return sessions.size();
		}
	}

	/**
	 * Get status info.
	 */
	public String getStatus() {
		Session[] sessions = getSessions();
		StringBuffer statusBuffer = new StringBuffer();
		statusBuffer.append("SessionMgr: " + sessions.length + " sessions \\n");
		for (int i = 0; i < sessions.length; i++) {
			statusBuffer.append(sessions[i] + "\\n");
		}
		return statusBuffer.toString();
	}

	/**
	 * Is Session present?

.
	 */
	public boolean hasSession(String anId) {
		synchronized (mutex) {
			return sessions.containsKey(anId);
		}
	}

	/**
	 * Add session.
	 */
	public void addSession(Session session) {
		synchronized (mutex) {
			sessions.put(session.getId(), session);
			sessionCacheDirty = true;
		}
		// log(session.getId() + " at " + session.getAddress() + " adding ");
		info(session.getId() + " at " + session.getAddress() + " added ");
	}

	/**
	 * Register session for removal.
	 */
	public Session removeSession(Session aSession) {
		synchronized (mutex) {
			Session session = (Session) sessions.remove(aSession.getId());
			if (session != null) {
				info(session.getId() + " at " + session.getAddress()
						+ " removed ");
			}
			sessionCacheDirty = true;
			return session;
		}
	}

	/**
	 * Starts us.
	 */
	public void start() throws PushletException {
		if (timer != null) {
			stop();
		}
		timer = new Timer(false);
		timer.schedule(new AgingTimerTask(), TIMER_INTERVAL_MILLIS,
				TIMER_INTERVAL_MILLIS);
		info("started; interval=" + TIMER_INTERVAL_MILLIS + "ms");
	}

	/**
	 * Stopis us.
	 */
	public void stop() {
		if (timer != null) {
			timer.cancel();
			timer = null;
		}
		synchronized (mutex) {
			sessions.clear();
		}
		info("stopped");
	}

	/**
	 * Create unique Session id.
	 */
	protected String createSessionId() {
		// Use UUID if specified in config (thanks Uli Romahn)
		if (Config.hasProperty(SESSION_ID_GENERATION)
				&& Config.getProperty(SESSION_ID_GENERATION).equals(
						SESSION_ID_GENERATION_UUID)) {
			// We want to be Java 1.4 compatible so use UID class (1.5+ we may
			// use java.util.UUID).
			return new UID().toString();
		}

		// Other cases use random name

		// Create a unique session id
		// In 99.9999 % of the cases this should be generated at once
		// We need the mutext to prevent the chance of creating
		// same-valued ids (thanks Uli Romahn)
		synchronized (mutex) {
			String id;
			while (true) {
				id = Rand.randomName(Config.getIntProperty(SESSION_ID_SIZE));
				if (!hasSession(id)) {
					// Created unique session id
					break;
				}
			}
			return id;
		}
	}

	/**
	 * Util: stdout printing.
	 */
	protected void info(String s) {
		Log.info("SessionManager: " + new Date() + " " + s);
	}

	/**
	 * Util: stdout printing.
	 */
	protected void warn(String s) {
		Log.warn("SessionManager: " + s);
	}

	/**
	 * Util: stdout printing.
	 */
	protected void debug(String s) {
		Log.debug("SessionManager: " + s);
	}

	/**
	 * Manages Session timeouts.
	 */
	private class AgingTimerTask extends TimerTask {
		private long lastRun = Sys.now();
		private long delta;
		private Method visitMethod;

		public AgingTimerTask() throws PushletException {
			try {
				// Setup Visitor Methods for callback from SessionManager
				Class[] argsClasses = { Session.class };
				visitMethod = this.getClass().getMethod("visit", argsClasses);
			} catch (NoSuchMethodException e) {
				throw new PushletException("Failed to setup AgingTimerTask", e);
			}
		}

		/**
		 * Clock tick callback from Timer.
		 */
		public void run() {
			long now = Sys.now();
			delta = now - lastRun;
			lastRun = now;
			debug("AgingTimerTask: tick");

			// Use Visitor pattern to loop through Session objects (see visit()
			// below)
			getInstance().apply(this, visitMethod, new Object[1]);
		}

		/**
		 * Callback from SessionManager during apply()
		 */
		public void visit(Session aSession) {
			try {
				// Age the lease
				aSession.age(delta);
				debug("AgingTimerTask: visit: " + aSession);

				// Stop session if lease expired
				if (aSession.isExpired()) {
					info("AgingTimerTask: Session expired: " + aSession);
					aSession.stop();
				}
			} catch (Throwable t) {
				warn("AgingTimerTask: Error in timer task : " + t);
			}
		}
	}
}

/*
 * $Log: SessionManager.java,v $ Revision 1.12 2007/12/04 13:55:53 justb
 * reimplement SessionManager concurrency (prev version was not thread-safe!)
 *
 * Revision 1.11 2007/11/23 14:33:07 justb core classes now configurable through
 * factory
 *
 * Revision 1.10 2007/11/10 14:47:45 justb make session key generation
 * configurable (can use uuid)
 *
 * Revision 1.9 2007/11/10 14:17:18 justb minor cosmetic changes just commit now
 *
 * Revision 1.8 2007/07/02 08:12:16 justb redo to original version of session
 * cache (with break, but nullify array first)
 *
 * Revision 1.7 2007/07/02 07:33:02 justb small fix in sessionmgr for holes in
 * sessioncache array (continue i.s.o. break)
 *
 * Revision 1.6 2006/11/18 12:13:47 justb made SessionManager constructor
 * protected to allow constructing derived classes
 *
 * Revision 1.5 2005/02/28 15:58:05 justb added SimpleListener example
 *
 * Revision 1.4 2005/02/28 12:45:59 justb introduced Command class
 *
 * Revision 1.3 2005/02/28 09:14:55 justb sessmgr/dispatcher factory/singleton
 * support
 *
 * Revision 1.2 2005/02/25 15:13:01 justb session id generation more robust
 *
 * Revision 1.1 2005/02/21 16:59:09 justb SessionManager and session lease
 * introduced
 */

接着··就大胆的改动了nl.justobjects.pushlet.core.EventPullSource，这里我改动了

abstract protected Event pullEvent();

改为了

abstract protected void pullEvent();

83    public void run() {
84        Log.debug(getClass().getName() + ": starting...");
85        alive = true;
86        while (alive) {
87            try {
88
89                Thread.sleep(getSleepTime());
90
91                // Stopped during sleep: end loop.
92                if (!alive) {
93                    break;
94                }
95
96                // If passivated wait until we get
97                // get notify()-ied. If there are no subscribers
98                // it wasts CPU to remain producing events...
99                synchronized (this) {
00                    while (!active) {
01                        Log.debug(getClass().getName() + ": waiting...");
02                        wait();
03                    }
04                }
05
06            } catch (InterruptedException e) {
07                break;
08            }
09
10            try {
11                // Derived class should produce an event.
12                Event event = pullEvent();
13
14                // Let the publisher push it to subscribers.
15                Dispatcher.getInstance().multicast(event);
16            } catch (Throwable t) {
17                Log.warn("EventPullSource exception while multicasting ", t);
18                t.printStackTrace();
19            }
20        }
21        Log.debug(getClass().getName() + ": stopped");
22    }
23}

改为了

	public void run() {
		Log.debug(getClass().getName() + ": starting...");
		alive = true;
		while (alive) {
			try {

				Thread.sleep(getSleepTime());

				// Stopped during sleep: end loop.
				if (!alive) {
					break;
				}

				// If passivated wait until we get
				// get notify()-ied. If there are no subscribers
				// it wasts CPU to remain producing events...
				synchronized (this) {
					while (!active) {
						Log.debug(getClass().getName() + ": waiting...");
						wait();
					}
				}

			} catch (InterruptedException e) {
				break;
			}

			try {
				// Derived class should produce an event.
				pullEvent();

				// Let the publisher push it to subscribers.
				//Dispatcher.getInstance().multicast(event);
			} catch (Throwable t) {
				Log.warn("EventPullSource exception while multicasting ", t);
				t.printStackTrace();
			}
		}
		Log.debug(getClass().getName() + ": stopped");
	}

		改动的原因··是原来的run线程启动以后会通过getEvent（）来获得event然后通过  Dispatcher.getInstance().multicast(event); 将事件广播了出去。我这里的改造以后的思路是，pullEvent（）不再返回event了，线程中也不去进行广播了，全部的操作，包含event的创建以及event的广播还是单播都在pullEvent（）中进行。

最后就是js的改动了，改动ajax-pushlet-client.js

给PL添加字段parameters；改动后例如以下：

var PL = {
	NV_P_FORMAT: 'p_format=xml-strict',
	NV_P_MODE: 'p_mode=pull',
	pushletURL: null,
	webRoot: null,
	sessionId: null,
	STATE_ERROR: -2,
	STATE_ABORT: -1,
	STATE_NULL: 1,
	STATE_READY: 2,
	STATE_JOINED: 3,
	STATE_LISTENING: 3,
	state: 1,
	<span style="color:#cc0000;">parameters:[],</span>
......}

_doRequest方法改动：

_doRequest: function(anEvent, aQuery) {

// Check if we are not in any error state

if (PL.state < 0) {

PL._setStatus('died (' + PL.state + ')');

return;

}





// We may have (async) requests outstanding and thus

// may have to wait for them to complete and change state.

var waitForState = false;

if (anEvent == 'join' || anEvent == 'join-listen') {

// We can only join after initialization

waitForState = (PL.state < PL.STATE_READY);

} else if (anEvent == 'leave') {

PL.state = PL.STATE_READY;

} else if (anEvent == 'refresh') {

// We must be in the listening state

if (PL.state != PL.STATE_LISTENING) {

return;

}

} else if (anEvent == 'listen') {

// We must have joined before we can listen

waitForState = (PL.state < PL.STATE_JOINED);

} else if (anEvent == 'subscribe' || anEvent == 'unsubscribe') {

// We must be listeing for subscription mgmnt

waitForState = (PL.state < PL.STATE_LISTENING);

} else {

// All other requests require that we have at least joined

waitForState = (PL.state < PL.STATE_JOINED);

}





// May have to wait for right state to issue request

if (waitForState == true) {

PL._setStatus(anEvent + ' , waiting... state=' + PL.state);

setTimeout(function() {

PL._doRequest(anEvent, aQuery);

}, 100);

return;

}





// ASSERTION: PL.state is OK for this request





// Construct base URL for GET

var url = PL.pushletURL + '?

p_event=' + anEvent;





// Optionally attach query string

if (aQuery) {

url = url + '&' + aQuery;

}





// Optionally attach session id

if (PL.sessionId != null) {

url = url + '&p_id=' + PL.sessionId;

if (anEvent == 'p_leave') {

PL.sessionId = null;

}

}

//这里是我改动的地方。我的数组中的偶数是參数名，奇数是參数内容。这里把我的參数拼接到了url中。

    if(PL.parameters.length > 0) {

url+="&" + PL.parameters[0] + "=" + PL.parameters[1];

   }  



PL.debug('_doRequest', url);

PL._getXML(url, PL._onResponse);





// uncomment to use synchronous XmlHttpRequest

//var rsp = PL._getXML(url);

//PL._onResponse(rsp);  */

},

额，改动完了。能够配置pushlet的相关參数，来使用pushlet了。

在web.xml中配置例如以下參数

	<servlet>
		<servlet-name>pushlet</servlet-name>
		<servlet-class>nl.justobjects.pushlet.servlet.Pushlet</servlet-class>
		<load-on-startup>3</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>pushlet</servlet-name>
		<url-pattern>/admin/pushlet.srv</url-pattern>
	</servlet-mapping>

这是pushlet配置的基本參数，这里我配置的是/admin/pushlet.srv，是由于项目的路径是localhost:8080/项目名 ,而我的页面是在localhost:8080/项目名/admin/以下。所以加了/admin/pushlet.srv。

假设你的页面就在项目文件夹下。就不用加前面的/admin了。

在sources.properties中配置例如以下參数

#
# Properties file for EventSource objects to be instantiated.
#
# Place this file in the CLASSPATH (e.g. WEB-INF/classes) or directly under WEB-INF.
#
# $Id: sources.properties,v 1.2 2007/11/10 14:12:16 justb Exp $
#
# Each EventSource is defined as <key>=<classname>
# 1. <key> should be unique within this file but may be any name
# 2. <classname> is the full class name
#
#
# Define Pull Sources here. These classes must be derived from
# nl.justobjects.pushlet.core.EventPullSource
# Inner classes are separated with a $ sign from the outer class.
source1=org.calonlan.soulpower.plug.HwPushlet$MessClazz
# TO BE DONE IN NEXT VERSION
# define Push Sources here. These must implement the interface
# nl.justobjects.pushlet.core.EventSource

这里把我的pushlet的实现类配置进去了。

最后就是怎样使用了。

单播：

package org.calonlan.soulpower.plug;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import nl.justobjects.pushlet.core.Dispatcher;
import nl.justobjects.pushlet.core.Event;
import nl.justobjects.pushlet.core.EventPullSource;
import nl.justobjects.pushlet.core.Session;
import nl.justobjects.pushlet.core.SessionManager;

public class HwPushlet {
	private static String driver = "com.mysql.jdbc.Driver";
	private static String dbName = "dlw";
	private static String userName = "root";
	private static String passWord = "root";
	private static String url = "jdbc:mysql://localhost:3306/";

	static public class MessClazz extends EventPullSource {

		@Override
		protected long getSleepTime() {
			return 1000 * 60 * 3;
		}

		@Override
		protected void pullEvent() {
			Session[] sessions = SessionManager.getInstance().getSessions();
			for (int i = 0; i < sessions.length; i++) {
				String userId = sessions[i].getEvent().getField("uid");
				Event event = Event.createDataEvent("/mipc/he");
				Connection conn = null;
				String x = "";
				try {
					Class.forName(driver);
					conn = DriverManager.getConnection(url + dbName, userName,
							passWord);
					Statement statement = conn.createStatement();
					String sql = "select * from weiorder where mystate='0' and bname='"
							+ userId + "'";
					ResultSet rst = statement.executeQuery(sql);
					if (rst.next()) {
						x = "1";
					} else {
						x = "2";
					}

				} catch (ClassNotFoundException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				} finally {
					try {
						conn.close();
					} catch (SQLException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
				event.setField("mess", x);
				Dispatcher.getInstance().unicast(event, sessions[i].getId());
			}
		}

	}

}

我这里是server的实现。在单播的时候查找前台传过来的uid中是否有消息，有的话返回一个1，没有就返回一个2。最重要的是Dispatcher.getInstance().unicast(event, sessions[i].getId());这一句，通过单播的形式把消息传递给指定session的用户。

页面js代码

<script type="text/javascript">
PL.parameters.push('uid');
PL.parameters.push('${user.username}');
PL._init();
PL.joinListen('/mipc/he');
function onData(event) {

	if(event.get("mess")=="1"){
		$.messager.show({
			title:'系统消息',
			msg:'您有新的订单请注意处理',
			timeout:0,
			showType:'slide'
		});
		document.getElementById('audio_player').play();
	}

    // 离开
    // PL.leave();
}
</script>

广播：广播的还js页面的请求就和官网一样了。pullEvent中也仅仅是简单的进行广播。代码例如以下

package org.calonlan.soulpower.plug;

import nl.justobjects.pushlet.core.Dispatcher;
import nl.justobjects.pushlet.core.Event;
import nl.justobjects.pushlet.core.EventPullSource;

public class HwPushlet {

	static public class MessClazz extends EventPullSource {

		@Override
		protected long getSleepTime() {
			return 1000 * 60 * 3;
		}

		@Override
		protected void pullEvent() {

			Event event = Event.createDataEvent("/mipc/he");
			String x = "";

			event.setField("mess", x);
			Dispatcher.getInstance().multicast(event);

		}

	}

}

额。时间比較仓促···近期项目太忙了，唉。这里简单的记录一下。也不知道这样的是不是非常落后或是非常复杂的改动方法。还忘高手们批评指正。改动后的jar包和js请在http://download.csdn.net/detail/u012613903/9483881下载。