求助。。。。。。。。。。。。。。。。

HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: java.lang.NullPointerExceptionorg.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:541)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause
java.lang.NullPointerExceptioncom.xurui.util.DBAccess.getConnection(DBAccess.java:38)com.xurui.util.TestSetUtil.getCourse(TestSetUtil.java:84)org.apache.jsp.teacher.login_jsp._jspService(login_jsp.java:68)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)javax.servlet.http.HttpServlet.service(HttpServlet.java:803)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs