<display-name>exam</display-name>
    <servlet>
        <description>
        </description>
        <display-name>Action</display-name>
        <servlet-name>Action</servlet-name>
        <servlet-class>exam.Action</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Action</servlet-name>
        <url-pattern>*.jspx</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>Index.jspx</welcome-file>
    </welcome-file-list>

     <display-name>Action</display-name>
        <servlet-name>Action</servlet-name>
        <servlet-class>exam.Action</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Action</servlet-name>
        <url-pattern>*.jspx</url-pattern>
    </servlet-mapping>

------解决方案--------------------

 <servlet-class>exam.Action</servlet-class>
这里写的应该是类名的目录把。
并且用Strust框架的话要有一个strust框架的一个过滤器。那个过滤器是整个strust框架的核心。


<filter>
     <filter-name>struts 2</filter-name>
     <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
 </filter>
<filter-mapping>
  <filter-name>struts 2</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>