comet4j 一个简单的实例

r囧r小猫 2022-06-17 00:49 191阅读 0赞

comet4j 一个简单的实例

# **一、****comet4j 简介** #

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 <td style="padding:0pt 5.4pt; border:0.5pt solid rgb(0,0,0); width:426.1pt"> Comet4J(Comet&nbsp;for&nbsp;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。 </td> 
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# **二、****功能简介** #

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 <td style="padding:0pt 5.4pt; border:0.5pt solid rgb(0,0,0); width:426.1pt"> ·&nbsp;推送消息广播。 ·&nbsp;推送定向消息。 ·&nbsp;提供连接上线前、上线、下线前、下线、发送消息等多种可处理事件。 ·&nbsp;消息缓存机制，确保长轮询工作模式下不丢失消息。 ·&nbsp;客户端正常下线，服务端可立即感知。 ·&nbsp;客户端异常停止工作，服务端可定时检查并感知。 ·&nbsp;以注册通道应用的方式，让开发者对框架功能进行扩展，实现自己的应用。 </td> 
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# **三、****框架特性** #

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 <td style="padding:0pt 5.4pt; border:0.5pt solid rgb(0,0,0); width:426.1pt"> ·&nbsp;独立小巧，不依赖于第三方包。 ·&nbsp;与应用紧密集成，无需独立应用或服务器。 ·&nbsp;与Session无关的连接机制，为开发人员提供最大程度的功能可控性。 ·&nbsp;面向事件编程，客户端与服务器端均为事件驱动开发模式，提供了良好的可扩展性机制。 ·&nbsp;各项性能参数均可配置。 ·&nbsp;支持多种主流浏览器，并支持Air应用环境。 &nbsp; </td> 
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# **四、****服务器支持情况** #

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 <td style="padding:0pt 5.4pt; border:0.5pt solid rgb(0,0,0); width:426.1pt"> Tomcat6、Tomcat7 </td> 
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# **五、****浏览器支持情况** #

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 <td style="background:rgb(255,255,255); padding:3.75pt; border:0.75pt solid rgb(204,204,204); width:14.65pt"> 浏览器/平台 </td> 
 <td style="background:rgb(255,255,255); border-width:0.75pt 0.75pt 0.75pt medium; border-style:solid solid solid none; border-color:rgb(204,204,204) rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 版本 </td> 
 <td style="background:rgb(255,255,255); border-width:0.75pt 0.75pt 0.75pt medium; border-style:solid solid solid none; border-color:rgb(204,204,204) rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 长轮询 </td> 
 <td style="background:rgb(255,255,255); border-width:0.75pt 0.75pt 0.75pt medium; border-style:solid solid solid none; border-color:rgb(204,204,204) rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 长连接 </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> Internet&nbsp;Explorer </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 6,7,8,9 </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> X </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> FireFox </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 3.0+(更底版本未知) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> Chrome </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 7.0+(更底版本未知) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> Safari </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 5+(更底版本未知) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> Opera </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 11.10+(更底版本未知) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> X </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> Air </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 1.5+(更底版本未知) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> IOS(Iphone/Ipad) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 3.1+(更底版本未知) </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> √ </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> Android </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 未测试 </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 未知 </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 未知 </td> 
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 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt; border-style:none solid solid; border-color:currentColor rgb(204,204,204) rgb(204,204,204); padding:3.75pt; width:14.65pt"> BlackBerry </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 未测试 </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 未知 </td> 
 <td style="background:rgb(255,255,255); border-width:medium 0.75pt 0.75pt medium; border-style:none solid solid none; border-color:currentColor rgb(204,204,204) rgb(204,204,204) currentColor; padding:3.75pt; width:14.65pt"> 未知 </td> 
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# **六、****简单的实例** #

** ****1.下载服务端jar文件**

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 <td style="padding:0pt 5.4pt; border:0.5pt solid rgb(0,0,0); width:426.1pt"> 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。 </td> 
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** **

**2.****下载客户端js文件**

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 <td style="padding:0pt 5.4pt; border:0.5pt solid rgb(0,0,0); width:426.1pt"> 下载【comet4j.js】到您的项目中，比如：WebContent\js目录下。 </td> 
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**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。 helloworld.html

<!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-0.0.2.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">...KB</body></html>

**服务端**

helloworld.java

package org.comet4j.demo.helloworld;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import org.comet4j.core.CometContext;import org.comet4j.core.CometEngine;public class HelloWorld 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) \{         \}\}

**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>