登陆时的有关问题

登陆时的问题
用strusts框架做的系统，comcat容器，配置都写好了，为什么在登陆提交后出这样的错误，问题在哪里呢？

type   Exception   report

message  

description   The   server   encountered   an   internal   error   ()   that   prevented   it   from   fulfilling   this   request.

exception  

javax.servlet.ServletException:   Servlet   execution   threw   an   exception
filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:123)


root   cause  

java.lang.NoClassDefFoundError
action.LoginAction.execute(LoginAction.java:81)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:123)


note   The   full   stack   trace   of   the   root   cause   is   available   in   the   Apache   Tomcat/5.5.9   logs.



------解决方案--------------------
java.lang.NoClassDefFoundError

是不是转型转错了
仔细检查一下是不是不小心敲错了
------解决方案--------------------
是不是没有找到类呢?
我的异常网推荐解决方案：The server encountered an internal error () that prevented it from fulfilling this request.,http://www..net/java-web/317.html