·<servlet-mapping>用来指定actionservlet可以处理哪些url。
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.actionservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
