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。
<?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
@Override
protected long getSleepTime() {
return 5000;
}
@Override
protected 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
在JSP中调用
<%@ 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！
工程部署后如下图展示
每次访问时，后台都会打印增加到管理中的用户信息，当关闭浏览器后，服务器会在超时后自动清理！
