<servlet>一定要在<servlet-mapping>前定义,
我有《用web.xml控制Web应用的行为.doc》这个文档,讲得很详细,有将近50页!<web-app>
<servlet>
   <servlet-name>Servlet2</servlet-name> 
   <servlet-class>untitled6.Servlet2</servlet-class>
</servlet>
<servlet>
   <servlet-name>Servlet3</servlet-name> 
   <servlet-class>untitled3.Servlet3</servlet-class>
</servlet>
<servlet-mapping>
   <servlet-name>Servlet2</servlet-name>
   <url-pattern>/servlet/untitled6.Servlet2</url-pattern>
</servlet-mapping>
<servlet-mapping>
   <servlet-name>Servlet3</servlet-name>
   <url-pattern>/servlet/untitled3.Servlet3</url-pattern>
</servlet-mapping></web-app>