Cannot create resource instance怎么解决？

老是出现这种提示
不知道是哪里出错
哪位能解释一下哪里有问题type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: javax.servlet.ServletException: javax.naming.NamingException: Cannot create resource instance
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:398)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause javax.servlet.ServletException: javax.naming.NamingException: Cannot create resource instance
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:862)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791)
org.apache.jsp.stu_005flogin_005fchk_jsp._jspService(stu_005flogin_005fchk_jsp.java:92)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause javax.naming.NamingException: Cannot create resource instance
org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:143)
javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
org.apache.naming.NamingContext.lookup(NamingContext.java:793)
org.apache.naming.NamingContext.lookup(NamingContext.java:140)
org.apache.naming.NamingContext.lookup(NamingContext.java:781)
org.apache.naming.NamingContext.lookup(NamingContext.java:140)
org.apache.naming.NamingContext.lookup(NamingContext.java:781)
org.apache.naming.NamingContext.lookup(NamingContext.java:140)
org.apache.naming.NamingContext.lookup(NamingContext.java:781)
org.apache.naming.NamingContext.lookup(NamingContext.java:153)
org.apache.naming.SelectorContext.lookup(SelectorContext.java:137)
javax.naming.InitialContext.lookup(InitialContext.java:392)
org.jingyang.beans.StuDBBean.<init>(StuDBBean.java:20)
org.apache.jsp.stu_005flogin_005fchk_jsp._jspService(stu_005flogin_005fchk_jsp.java:67)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.20 logs.