在struts 中如何用FileUpload 的组件呢？

Question

给我抛出一个
Servlet execution threw an exception
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:260)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at com.linkage.filter.SecurityFilter.doFilter(SecurityFilter.java:36)怎么回事呢？