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Comet4J(Comet for Java)是一个纯粹基于AJAX(XMLHTTPRequest)的服务器推送框架，消息以JSON方式传递，具备长轮询、长连接、自动选择三种工作模式。
我上传上原始的开发别的人开发包
在这里
Tomcat6、Tomcat7
支持XMLHTTPRequest对象的浏览器均可支持长轮询工作模式，但不一定能够支持长连接。
浏览器/平台
版本
1.下载服务端jar文件
2.下载客户端js文件
3.修改服务器配置文件
客户端
服务端
配置
准备工作
1.下载服务端jar文件
Comet4J目前仅支持Tomcat6、7版本，根据您所使用的Tomcat版本下载【comet4j-tomcat6.jar】或【comet4j-tomcat7.jar】文件放置到WEB项目的WEB-INF\lib目录下。
2.下载客户端js文件
下载【comet4j.js】到您的项目中，比如：WebContent\js目录下。
3.修改服务器配置文件
因为Comet4J工作在NIO方式下，所以我们需要调整服务器连接器配置，更换为NOI连接器。 打开server.xml文件将找到原先的连接器配置：
<Connector executor="tomcatThreadPool" port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />
替换为：
<Connector URIEncoding="UTF-8" connectionTimeout="20000" port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" redirectPort="8443"/>
客户端
我们利用Comet4J开发一个每隔一秒向所有客户端推送服务器的剩余内存大小。 comet4jpublishtoclient.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Comet4J Hello World</title> <script type="text/javascript" src="js/comet4j/comet4j.js"></script> <script type="text/javascript"> function init(){ var kbDom = document.getElementById(‘kb‘); JS.Engine.on({ hello : function(kb){//侦听一个channel kbDom.innerHTML = kb; } }); JS.Engine.start(‘conn‘); } </script> </head> <body onload="init()"> 剩余内存：<span id="kb">...</span>KB </body> </html>
服务端
helloworld.java
package com.axy.servletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import org.comet4j.core.CometContext; import org.comet4j.core.CometEngine; public class publishMessageToClient implements ServletContextListener { private static final String CHANNEL = "hello"; public void contextInitialized(ServletContextEvent arg0) { CometContext cc = CometContext.getInstance(); cc.registChannel(CHANNEL);//注册应用的channel Thread helloAppModule = new Thread(new HelloAppModule(), "Sender App Module"); helloAppModule.setDaemon(true); helloAppModule.start(); } class HelloAppModule implements Runnable { public void run() { while (true) { try { Thread.sleep(1000); } catch (Exception ex) { ex.printStackTrace(); } CometEngine engine = CometContext.getInstance().getEngine(); engine.sendToAll(CHANNEL, Runtime.getRuntime().freeMemory()/1024); } } } public void contextDestroyed(ServletContextEvent arg0) { } }
网上大部分的这样的配置
web.xml
<listener> <description>Comet4J容器侦听</description> <listener-class>org.comet4j.core.CometAppListener</listener-class> </listener> <servlet> <description>Comet连接[默认:org.comet4j.core.CometServlet]</description> <display-name>CometServlet</display-name> <servlet-name>CometServlet</servlet-name> <servlet-class>org.comet4j.core.CometServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>CometServlet</servlet-name> <url-pattern>/conn</url-pattern> </servlet-mapping> <listener> <description>HelloWorld</description> <listener-class>org.comet4j.demo.helloworld.HelloWorld</listener-class> </listener>
我的含有struct2,我的配置文件是
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <display-name>signalweb</display-name> <!-- comet4j --> <listener> <description>Comet4J容器侦听</description> <listener-class>org.comet4j.core.CometAppListener</listener-class> </listener> <servlet> <description>Comet连接默认:org.comet4j.core.CometServlet</description> <display-name>CometServlet</display-name> <servlet-name>CometServlet</servlet-name> <servlet-class>org.comet4j.core.CometServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>CometServlet</servlet-name> <url-pattern>/conn</url-pattern> </servlet-mapping> <listener> <description>publishMessageToClient</description> <listener-class>com.axy.servletContext.publishMessageToClient</listener-class> </listener> <!-- next is struct2 --> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </context-param> </web-app>
下面是我在SSHE项目中亲自验证,结果如下
Comet4J推技术在SSHE三大框架中应用-linux下亲测可用
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原文地址：http://www.cnblogs.com/lixinhai/p/4895526.html
