J2EE项目在本地Jetty上能启动运行，但是部署到SAE上报错?报错

事情的经过是这样的。在我的web.xml下配置了下面这个过滤器。

<filter>  
	  <filter-name>Set Character Encoding</filter-name>  
	  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>  
	  <init-param>  
	  <param-name>encoding</param-name>  
	  <param-value>utf8</param-value>  
	  </init-param>  
	</filter>  
 	<filter-mapping>  
  		<filter-name>Set Character Encoding</filter-name>  
  		<url-pattern>/*</url-pattern>  
 	</filter-mapping>

然后我就把上面那段xml注释了，我想反正只是编码方面的无所谓。

接着第二个问题又出现了，在WEB.xml中

<!-- spring mvc servlet -->
<servlet>
<description>spring mvc servlet</description>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<description>spring mvc 配置文件</description>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:com/StudentCommunityManagementSystem/config/spring/spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
结果又报

java.lang.ClassCastException: org.springframework.web.servlet.DispatcherServlet cannot be cast to javax.servlet.Servlet

但是我查看了org.springframework.web.servlet.DispatcherServlet它是 implements Servlet的。

求大神解释啊，急死宝宝了