基于javaweb的网站开发，重装系统后出现HTTP Status 500错误，请问怎么解决？

Question

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.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:502)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:430)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause
java.lang.NullPointerException
com.util.DBO.close(DBO.java:55)
com.bean.SystemBean.getSiteInfo(SystemBean.java:91)
org.apache.jsp.index_jsp._jspService(index_jsp.java:100)
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:388)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.
Apache Tomcat/6.0.35

Answer 1

org.apache.jasper.JasperException: java.lang.NullPointerException这里说是空值错误，而且报错页面是index.jsp，看看是不是你这个页面里得java代码有空值，重装系统是不是数据库没了？