strtus2.5报错显示：java.lang.ClassCastException:StrutsPrepareAndExecuteFilter cannot be cast to javax.servlet.Servlet

Previously written struts project has not been reported this wrong, now write a little practice, they reported this wrong, look carefully for a long time detail than is silent on the error found by the previous project, the problem lies in web.xml, I the struts need to configure filters written servlet, it has not been found. It is stupid.