serverpush实现
前段时间做一个Demo，需要在里面实现实时的系统内存、CPU、线程等信息。考虑Ajax的Polling来实现，但发现CPU很高，频繁的Ajax访问，服务器受不了呀。目前，初步实现push的服务器还不成熟。servlet3.0，Tomcat等有实现，但很麻烦。
幸好08年有DWR的使用经历，DWR3.0的反向功能，让我看到了希望。下面来说说他实现的一个及时聊天吧。
1.导入dwr.jar
2.servlet配置
<servlet><servlet-name>dwr-invoker</servlet-name><servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class><init-param><param-name>debug</param-name><param-value>true</param-value></init-param><init-param><param-name>activeReverseAjaxEnabled</param-name><param-value>true</param-value></init-param><load-on-startup>1</load-on-startup></servlet><servlet-mapping><servlet-name>dwr-invoker</servlet-name><url-pattern>/dwr/*</url-pattern></servlet-mapping> 3.新建一个java后台类
public class TestClass{ int i = 0; public String testMethod1(String name) { return "Hello," + name; } public void send(final String msg) { Browser.withCurrentPage(new Runnable() { public void run() { ScriptSessions.addFunctionCall("receive", msg); } }); }}4.编写dwr.xml配置文件
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd"><dwr><allow><create creator="new" javascript="testClass"scope="application"><param name="class" value="dwr.TestClass" /><include method="testMethod1" /><include method="send" /></create></allow></dwr> 5.前段代码的编写
<script src='dwr/interface/testClass.js'></script><script src='dwr/engine.js'></script><script src='dwr/util.js'></script><body onload=dwr.engine.setActiveReverseAjax(true);> <input type="text" id='shuo' /> <input type="button" value='send' id="btn" /> <div id="kkk2"></div> <script type="text/javascript"> document.getElementById('btn').onclick = function(){ var msg = document.getElementById('shuo').value; testClass.send(msg); document.getElementById('shuo').value=''; } function receive(msg){ var d = document.createElement('div'); d.innerHTML = msg; document.getElementById('kkk2').appendChild(d); } </script></body> 现在打开多个浏览器测试吧！！！
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