看似很简单的错误，不知道怎么解决了　　帮帮忙

description The server encountered an internal error () that prevented it from fulfilling this request.exception javax.servlet.ServletException: com/justhis/filter/RegexFilter
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:846)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:779)
org.apache.jsp.cwcNews.test_jsp._jspService(org.apache.jsp.cwcNews.test_jsp:334)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:99)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:325)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.lang.NoClassDefFoundError: com/justhis/filter/RegexFilter
cwcNews.managerNews.<init>(managerNews.java:27)
org.apache.jsp.cwcNews.test_jsp._jspService(org.apache.jsp.cwcNews.test_jsp:89)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:99)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:325)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)什么错误啊！！！