整个例子的源码下载：http://pan.baidu.com/s/1gfFYSbp
Comet4J目前仅支持Tomcat6、7版本，根据您所使用的Tomcat版本下载【comet4jtomcat6.jar】或【comet4j-tomcat7.jar】文件放置到WEB项目的WEB-INFlib目录下。
本文下载comet4j-tomcat7.jar, 下载地址：http://pan.baidu.com/s/1eSBXmfS
下载客户端js文件
下载【comet4j.js】到您的项目中，比如：WebContentJScometd目录下。
下载地址：http://pan.baidu.com/s/1qXYxkYg
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一个定时增长的数字。
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Cometd首页</title>
<script type="text/javascript" src="./JS/cometd/comet4j.js"></script>
<script type="text/javascript">
var projectPath = '<%= request.getContextPath()%>';
function cometdCallback(text){
var kbDom = document.getElementById('num1');
kbDom.innerHTML = text;
}
function init() {
JS.Engine.on({
number : cometdCallback
});
JS.Engine.start(projectPath+'/conn');
}
</script>
</head>
<body onload="init()">
数字3：
<span id="num1">...</span>
</body>
</html>
其中，<%=request.getContextPath()%>是为了解决相对路径的问题，可返回站点的根路径。
package com.cvicse.ump.cometd;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import org.comet4j.core.CometContext;
public class CometdTestClass implements ServletContextListener {
private static final String CHANNEL_NUM = "number";
private static int number = 0;
@Override
public void contextDestroyed(ServletContextEvent arg0) {
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
CometContext.getInstance().registChannel(CHANNEL_NUM);
Thread timeThread = new Thread(new TimeThread(),"numTimeThread");
timeThread.setDaemon(true);//设置为守护线程
timeThread.start();
}
class TimeThread implements Runnable{
@Override
public void run() {
while(true){
CometContext.getInstance().getEngine().sendToAll(CHANNEL_NUM, number++);
System.out.println(CHANNEL_NUM+": "+number);
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
配置
web.xml
<?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" id="WebApp_ID" version="3.0">
<display-name>cometd</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<listener>
<description>Comet4J容器侦听</description>
<listener-class>org.comet4j.core.CometAppListener</listener-class>
</listener>
<listener>
<listener-class>com.cvicse.ump.cometd.CometdTestClass</listener-class>
</listener>
<servlet>
<description>Comet连接[默认:org.comet4j.core.CometServlet]</description>
<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>
</web-app>
特此感谢：http://blog.csdn.net/u012726702/article/details/73928421