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ajax开源项目dwr的使用：
?利用DWR可以在客户端利用JavaScript直接调用服务端的Java方法并返回值
?给JavaScript就好像直接本地客户端调用一样.
?1：下载dwr.jar文件，将其加入到web工程的lib下；
?2：在web.xml文件中配置如下信息：
??<servlet>
? ???<servlet-name>dwr-invoker</servlet-name>
? ???<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
??</servlet>
??<servlet-mapping>
? ???<servlet-name>dwr-invoker</servlet-name>
???<url-pattern>/dwr/*</url-pattern>
??</servlet-mapping>
??? 其中url-pattern中必须配置为 “/dwr/* ”，不能为工程的名称！！
?
?3：在web.xml同级中增加文件dwr.xml，此文件是javaScript中调用的方法，影射到class类
??例如：
?? <!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://www.getahead.ltd.uk/dwr//dwr20.dtd">
??<dwr>
?? <!-- without allow, DWR isn't allowed to do anything -->
? ???<allow>
??? ???<create creator="new" javascript="MyTest" scope="application">
????? ????<param name="class" value="com.test.ajax.DWRTest"/>
??? ???</create>
??? ???<create scope="application" creator="new" javascript="showData">
??? ????<param name="class" value="com.test.ajax.HelloName"/>
??? ???</create>
? ???</allow>
??</dwr>
?在allow节点中定义要影射的class类，并且给其class类起一个javaScript的名字，以便在
?javaScript中调用。
?
?4：然后定义class文件
??package com.test.ajax;
??public class DWRTest
??{
???public DWRTest(){
?????
??? }
??? public String getMyName(){
???? return "hello_ajax";
??? }
??}
??
??/**
??*---------------------------------------------------
??**/
??package com.test.ajax;
??public class HelloName
??{
???private String userName ;
???public HelloName(){??
???}
???/**
??? * @return Returns the userName.
??? */
???public String getUserName()
???{
????return "helloTest";
???}
???/**
??? * @param userName The userName to set.
??? */
???public void setUserName(String userName)
???{
????this.userName = userName;
???}
??}
?5: 这时就可以在html或jsp中调用此class文件了，调用方式如下
??一下为测试的 html文件
????
???<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
???<html>
???<head>
???? <title>DWR - My First AJAX</title>
???? <meta http-equiv="Content-Type" content="text/html; charset=gb2312">
???? <script type='text/javascript' src='dwr/interface/MyTest.js'></script>
???? <script type='text/javascript' src='dwr/interface/showData.js'></script>
???? <script type='text/javascript' src='dwr/engine.js'></script>
???? <script type='text/javascript' src='dwr/util.js'></script>
???? <script language="javascript">
????? var mycall=function callBack(data){
????? DWRUtil.setValue("demo1",data);
????? DWRUtil.setValue("demo2","leo_wang");
????? DWRUtil.setValue("userName",data);
????? }
????? function showMyName(){
?????? //MyTest.getMyName(mycall);
?????? showData.getUserName(mycall);
????? }
???
????? function clearName(){
?????? demo1.value="";
?????? demo2.value="";
????? }
???? </script>
???? </head>
???<body>
???<h1>Ajax Test Page</h1>
???<input type="button" value="setMyName" onclick="javascript:showMyName()">
???<input type="button" value="Clear" onclick="javascript:clearName()"><br>
???<input type="text" id="demo1">
???<input type="text" id="demo2">
???<input type="test" id="userName">userName
???</body></html>
??在调用javaScript前要先引入刚才在dwr.xml中定义的javaScript
??<script type='text/javascript' src='dwr/interface/MyTest.js'></script>
??<script type='text/javascript' src='dwr/interface/showData.js'></script>
??<script type='text/javascript' src='dwr/engine.js'></script>
??<script type='text/javascript' src='dwr/util.js'></script>
??前面两行是我们刚才定义的javaScript的引入，后面两行是dwr中的本身定义的javaScript
??
??ok(完）
??
????
??
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