WEB-INF下的web.xml导致404找不到页面错误???????
在工程的WEB-INF下的web.xml文件如下，单访问index.jsp时却一直提示404找不到页面错误，删掉下面代码中<filter>...</filter>以及<filter-mapping>...</filter-mapping>内容后就能正常访问index.jsp，请教各位高手是什么原因啊？

<?xml version="1.0" encoding="ISO-8859-1"?>
<!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>fybg</display-name>
 <filter>
  <filter-name>Set Web Application Character Encoding</filter-name>
  <filter-class>com.eastsoft.servlets.SetEncodeFilter</filter-class>
  <init-param>
  <param-name>defaultencoding</param-name>
  <!--<param-value>iso-8859-1</param-value>-->
  <param-value>GBK</param-value>
  </init-param>
  </filter>
  <filter-mapping>
  <filter-name>Set Web Application Character Encoding</filter-name>
  <url-pattern>/*</url-pattern>
  </filter-mapping>

<servlet>
  <servlet-name>Attarchdown</servlet-name>
  <servlet-class>Attarchdown</servlet-class>
  </servlet>
<servlet-mapping>
  <servlet-name>Attarchdown</servlet-name>
  <url-pattern>/webmail/servlet/Attarchdown</url-pattern>
  </servlet-mapping>
<session-config>
<session-timeout>30</session-timeout>
</session-config>
<welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
<welcome-file>index.html</welcome-file>
  </welcome-file-list>
</web-app>


------解决方案--------------------
看看后台报什么错先吧
<param-name>defaultencoding </param-name> 
<!-- <param-value>iso-8859-1 </param-value>--> 
<param-value>GBK </param-value> 
怎么这些都有空格，本来就有还是你发布的时候加上去的。
如果本来就有建议你去掉这些空格