1.在lib中加入相应的dwr.jar包
2.在web.xml中加入以下代码：
<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>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
3.在web-inf目录下新建dwr.xml文件，加入一个简单的配置：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://www.getahead.ltd.uk/dwr/dwr20.dtd">
<dwr>
<create creator="new" javascript="service">
<param name="class" value="helloWorld.Service"/>
</create>
</allow>
</dwr>
4.新建一个servlet类，
public class Service {
public String sayHello(String yourName){
return yourName;
}
}
5.新建一个jsp页面如下：
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
<script type='text/javascript' src='/dwr2/dwr/interface/service.js'></script>
<script type='text/javascript' src='/dwr2/dwr/engine.js'></script>
<script type='text/javascript' src='/dwr2/dwr/util.js'></script>
<script type="text/javascript">
function firstdwr(){
service.sayHello("yangjunwei",callback);
}
function callback(d){
alert(d);
}
</script>
</head>
<body>
<input type="button" onclick="firstdwr()"/>
</body>
</html>
当点击按钮时，就会弹出yangjunwei，这就完成了一个简单的dwrajax交互