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【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。

服务端

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