服务器jsp推送

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Pushlet(一种comet 架构的实现)是基于Servlet 机制,数据从server端的Java 对象直接推送(push)到客户端浏览器的(动态)HTML 页面,而无需任何Java applet 或者插件的帮助。

  • 在MyEclipse中创建工程。附件包含了从官方下载的Pushlet包已经本次的源码包,直接导入到开发工具即可。
  • 在创建的工程中增加pushlet.jar,log4j.jar。拷贝pushlet.properties,sources.properties到WEB-INF下。拷贝ajax-pushlet-client.js到WebRoot下。
  • 配置web.xml
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE web-app    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"    "http://java.sun.com/dtd/web-app_2_3.dtd"><!-- $Id: web.xml,v 1.7 2005/02/21 17:21:49 justb Exp $ --><web-app><!-- Define the pushlet servlet --><servlet><servlet-name>pushlet</servlet-name><servlet-class>nl.justobjects.pushlet.servlet.Pushlet</servlet-class><load-on-startup>3</load-on-startup></servlet><!-- Define the Servlet Mappings. --><!-- The pushlet --><servlet-mapping><servlet-name>pushlet</servlet-name><url-pattern>/pushlet.srv</url-pattern></servlet-mapping></web-app>

后台代码HelloWorldPlushlet.java,该类包含一个内部类

package com;import nl.justobjects.pushlet.core.Event;import nl.justobjects.pushlet.core.EventPullSource;public class HelloWorldPlushlet {static public class HwPlushlet extends EventPullSource {// 休眠五秒@Overrideprotected long getSleepTime() {return 5000;}@Overrideprotected Event pullEvent() {Event event = Event.createDataEvent("/cuige/he");event.setField("mess", "hello,world!Plushlet!");return event;}}}

 sources.properties清理其他,定义自己发布的内容

source1=com.HelloWorldPlushlet$HwPlushlet

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><meta http-equiv="Pragma" content="no-cache" /><script type="text/javascript" src="ajax-pushlet-client.js"></script><script type="text/javascript">PL._init(); PL.joinListen('/cuige/he');function onData(event) { alert(event.get("mess")); // 离开// PL.leave();}</script></head><body><center><h1>my first pushlet!</h1></center></body></html>

  •  将工程部署到Tomcat后访问,该页面以五秒钟一个间隔,收到后台传来的数据!

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