打开web页错误

Question

HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:500)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:413)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause java.lang.NullPointerException
org.apache.jsp.login_jsp._jspService(login_jsp.java:72)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:371)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.35 logs.怎么解决？

Answer 1

http://bbs.51testing.com/viewthread.php?tid=124237

Answer 2

java.lang.NullPointerException
看看login页面

Answer 3

<%@ page contentType="text/html;charset=gb2312" language="java"%>
<%@ page import="java.io.*,java.sql.*"%>
<jsp:useBean id="rst" scope="page" class="com.mingri.dbconn.DBResult"/>
<jsp:useBean id="calendar" scope="page" class="com.mingri.showtime.ShowTime"/>
<%
   request.setCharacterEncoding("gb2312");//对请求进行统一编码，能正常接受到中文
   String username=request.getParameter("username"); //接收表单中的username属性
   String password=request.getParameter("password");//接收表单中的password属性
   String str="select * from tb_user where "+
               "username='"+username+"' and password='"+password+"'";
   ResultSet rs=rst.getResult(str);//执行SQL语句获得结果集对象
   session.setAttribute("isLog",new String("0"));//判断用户是否登陆，当isLog的属性为0时，说明用户并没有登陆
   if(!rs.next())//结果集没有找到所要查找的行
   {
    out.println("<script language='javascript'>alert('用户名或密码错误');"+
                "parent.location.href='login.html';</script>");
   }
   else
   {
     session.setAttribute("username",rs.getString("username"));//保存登录信息到session对象中
     session.setAttribute("password",rs.getString("password"));
     session.setAttribute("isLog",new String("1"));//将isLog属性设置为1
     //获得用户上次登陆系统的时间
     session.setAttribute("userLastLogTime",rs.getString("userLastLogTime"));
     String strsql=calendar.getDate();
     int id=rs.getInt("ID");
     //将该用户本次登陆系统的时间在用户信息表中更新
     String strUpdate="update tb_user set userLastLogTime='"+strsql+"' where ID="+id+"";
     rst.getResult(strUpdate);//执行SQL语句
     response.sendRedirect("chat.jsp");//登陆成功后转到系统主页面
   }
%>login页面代码