这是代码:<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<%@ page contentType="text/html; charset=gb2312"%>
<%@ page language="java" import="java.sql.*,mypackage.*"%>
<jsp:useBean id="SqlBean" scope="page" class="mypackage.SQLServerConnBean"/>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>2列左侧固定右侧自适应宽度+头部+尾部——<a href="http://www.aa25.cn">标准之路www.aa25.cn</a></title>
<link href="layout.css" rel="stylesheet" type="text/css" />
<meta name="Keywords" content="标准之路,www.aa25.cn,网页标准布局,DIV+CSS" />
<meta name="" content="标准之路,www.aa25.cn,网页标准布局,DIV+CSS" />
<meta name="author" content"×××,有问题请到www.68css.cn网站留言" />
<meta name="Description" content="本套网页标准布局模板是由标准之路(www.aa25.cn)制作完成,如果您要转载,请保留版权" />
</head><body>
<div id="container">
  <div id="header">
    <div align="center">
      <table width="453" height="92" border="0">
        <tr>
          <td width="447">政法学院成绩查询</td>
        </tr>
      </table>
    </div>
  </div>
  <div id="mainContent">
    <div id="sidebar">
      <table width="200" height="211" border="0">
        <tr>
          <td>
  <p>&nbsp;</p>
   <p>
     <%  
      String id=request.getParameter("textfield");
  String pw  =request.getParameter("textfield2");
  String sf=request.getParameter("radiobutton");
  if("t".equals(sf))
  {
String sql = "select * from teacher where teano='"+id+"' and pwt='"+pw+"'";
SqlBean.OpenConn();
    ResultSet rs=SqlBean.executeQuery(sql);
    //如果记录集非空,表明有匹配的用户名和密码,登陆成功
  if ( rs.next())
 
  {
session.setAttribute("id",id);
response.sendRedirect("teacher.jsp");
}
    else
{
response.sendRedirect("/loginwrong.jsp");
}
     }
 else
 {
 String sql1 = "select * from student where sno='" + id + "' and pw= '" + pw + "'"; 
 SqlBean.OpenConn();

 ResultSet rs=SqlBean.executeQuery(sql1);
if ( rs.next ( ) )
{
session.setAttribute("id",id);
response.sendRedirect("stu/students.jsp");
}
 else
{
response.sendRedirect("/loginwrong.jsp");
}
    }
%>
</body>
</html>
这是报错信息:
 Exception reportmessage 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:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
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 java.lang.NullPointerException
org.apache.jsp.check_jsp._jspService(check_jsp.java:126)
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/6.0.18 logs.

解决方案 »

  1.   

    对啊,rs.next ( ) 是空的rs没赋上值
      

  2.   

    :<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <%@ page contentType="text/html; charset=gb2312"%>
    <%@ page language="java" import="java.sql.*,mypackage.*"%>
    <jsp:useBean id="SqlBean" scope="page" class="mypackage.SQLServerConnBean"/>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
    <title>2列左侧固定右侧自适应宽度+头部+尾部——<a href="http://www.aa25.cn">标准之路www.aa25.cn</a></title>
    <link href="layout.css" rel="stylesheet" type="text/css" />
    <meta name="Keywords" content="标准之路,www.aa25.cn,网页标准布局,DIV+CSS" />
    <meta name="" content="标准之路,www.aa25.cn,网页标准布局,DIV+CSS" />
    <meta name="author" content"×××,有问题请到www.68css.cn网站留言" />
    <meta name="Description" content="本套网页标准布局模板是由标准之路(www.aa25.cn)制作完成,如果您要转载,请保留版权" />
    </head><body>
    <div id="container">
      <div id="header">
      <div align="center">
      <table width="453" height="92" border="0">
      <tr>
      <td width="447">政法学院成绩查询</td>
      </tr>
      </table>
      </div>
      </div>
      <div id="mainContent">
      <div id="sidebar">
      <table width="200" height="211" border="0">
      <tr>
      <td>
    <p>&nbsp;</p>
      <p>
      <%   
      String id=request.getParameter("textfield");
    String pw =request.getParameter("textfield2");
    String sf=request.getParameter("radiobutton");
    if("t".equals(sf))
    {
    String sql = "select * from teacher where teano='"+id+"' and pwt='"+pw+"'";
    SqlBean.OpenConn();
      ResultSet rs=SqlBean.executeQuery(sql);
      //如果记录集非空,表明有匹配的用户名和密码,登陆成功
      if ( rs.next())
      
      {
    session.setAttribute("id",id);
    response.sendRedirect("teacher.jsp");
    }
      else
    {
    response.sendRedirect("/loginwrong.jsp");
    }
      }
    else
    {
    String sql1 = "select * from student where sno='" + id + "' and pw= '" + pw + "'";  
    SqlBean.OpenConn();ResultSet rs=SqlBean.executeQuery(sql1);
    if ( rs.next ( ) )
    {
    session.setAttribute("id",id);
    response.sendRedirect("stu/students.jsp");
    }
     else
    {
    response.sendRedirect("/loginwrong.jsp");
    }
      }
    %>
    </body>
    </html>
    这是报错信息:
     Exception reportmessage  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(JspServletWrapperwww.163xyx.com.java:522)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
    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  java.lang.NullPointerException
    org.apache.jsp.check_jsp._jspService(check_jsp.java:126)
    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/6.0.18 logs.
    什么情况啊??好迷茫
      

  3.   

    。首先、你确定你的 connection 是不是连接上了。
            其次、确定你的PreparedStatement 或者 Statement 不为空,创建成功了
            然后、你在看看。。还抱吗