web.xml的问题
我的web应用写的web.xml文件如下：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">

  <web-app id="WebApp">
  <display-name>CCAS</display-name>
  <filter>
  <filter-name>CharacterEncodingFilter</filter-name>  
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>  
<param-name>encoding</param-name>  
<param-value>GBK</param-value>  
  </init-param>  
  <init-param>  
<param-name>forceEncoding</param-name>  
<param-value>true</param-value>  
  </init-param> 
  </filter>
<filter-mapping>  
<filter-name>CharacterEncodingFilter</filter-name>  
<url-pattern>/*</url-pattern>  
</filter-mapping>  
   
  <servlet>
  <servlet-name>CMain</servlet-name>
  <display-name>CMain</display-name>
  <servlet-class>com.visionsky.controls.Main</servlet-class>
  <init-param>
  <param-name>log4j</param-name>
  <param-value>/WEB-INF/log4j.properties</param-value>
  </init-param>
  <init-param>
  <param-name>ImageRoot</param-name>
  <param-value>/imgdoc/</param-value>
  </init-param>
  <init-param>
  <param-name>maxUploadSize</param-name>
  <param-value>5024000</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
  </servlet>  
  <servlet-mapping>
  <servlet-name>CMain</servlet-name>
  <url-pattern>/CMain</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
  <welcome-file>BLogon.jsp</welcome-file>
  </welcome-file-list>
  <resource-ref>
  <res-ref-name>jdbc/CCASDataSource</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
  <res-sharing-scope>UnShareable</res-sharing-scope>
  </resource-ref>
  </web-app>

奇怪的是当加上过滤器时：
  <filter>
  <filter-name>CharacterEncodingFilter</filter-name>  
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>  
<param-name>encoding</param-name>  
<param-value>GBK</param-value>  
  </init-param>  
  <init-param>  
<param-name>forceEncoding</param-name>  
<param-value>true</param-value>  
  </init-param> 
  </filter>
<filter-mapping> &n