HTTP Status 500 - An exception occurred processing JSP page /chkuser.jsp at line 10


type Exception report

message An exception occurred processing JSP page /chkuser.jsp at line 10

description The server encountered an internal error that prevented it from fulfilling this request.

exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /chkuser.jsp at line 10

7:
8:      ResultSet rst=chk.executeQuery("select * from vip_info where vip_id='"+vip_id+"' and vip_password = '"+password+"'");
9: int yes=0;
10: if(rst.next())
11: {
12:     session.setAttribute("vip_id",vip_id);
13:      yes=1;


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)



root cause
java.lang.NullPointerException
    org.apache.jsp.chkuser_jsp._jspService(chkuser_jsp.java:81)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)



note The full stack trace of the root cause is available in the Apache Tomcat/7.0.56 logs.

ResultSet rst=chk.executeQuery("select * from vip_info where vip_id='"+vip_id+"' and vip_password = '"+password+"'");
这句话查询出来的结果 rst 为空。
if(rst.next())
这句话需要判断 rst是否为空,修改后的代码如下：
if(rst != null && rst.next())

感觉学到了很多