使用DWR完成HelloWorld.
一、到DWR的官方网站上下载dwr.jar包。将其放到项目的lib目录下。开始做第一个dwr程序。
二、web.xml配置如下：
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><display-name>dwrtest</display-name><servlet><servlet-name>dwr-invoke</servlet-name><servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class><init-param><param-name>debug</param-name><param-value>true</param-value></init-param></servlet><servlet-mapping><servlet-name>dwr-invoke</servlet-name><url-pattern>/dwr/*</url-pattern></servlet-mapping> <welcome-file-list> <welcome-file>Index.jsp</welcome-file> </welcome-file-list></web-app>
?
三、在web.xml同目录下新建dwr.xml文件，内容如下：
<?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 javascript="JDate" creator="new"><param name="class" value="java.util.Date"/></create><create javascript="Hello" creator="new"><param name="class" value="com.dwr.HelloWorld"/></create></allow></dwr>
?
四、Index.jsp内容如下：
<%@ 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 HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>"> <title>DWR's HelloWorld</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--><script type='text/javascript' src='dwr/interface/Hello.js'></script><script type='text/javascript' src='dwr/engine.js'></script><script type='text/javascript' src='dwr/util.js'></script><script type='text/javascript' src='hello.js'></script> </head> <body> <input id="user" type="text"/><input type="button" value="您好" onClick="hello()"><div id="result"></div> </body></html>
?
五、在Index.jsp同目录下新建hello.js文件，内容如下：
function hello(){var user = $('user').value;Hello.sayHello(user,callback);}function callback(msg){if (typeof window['DWRUtil'] == 'undefined') window.DWRUtil = dwr.util; DWRUtil.setValue('result',msg);}?六、部署运行程序，我的可以看到结果。
1 楼 bo_hai 2011-02-12 接下来开始分析dwr的工作原理。 2 楼 bo_hai 2011-02-12 DWR的工作原理是通过动态把JAVA生成为JavaScript。它的代码就像Ajax魔法一样，你感觉调用就像发生在浏览器端，但是实际上代码调用发生在服务端，DWR负责数据的传递和转换。这种从JAVA到JavaScript的远程调用功能的方式使用DWR用起来有种非常橡RMI或者SOAP的常规RPC机制，而且DWR的优点在于不需要任何的网页浏览器插件就能运行在网页上。