登陆数据库问题，请高手帮忙看看！

Question

C:\JBuilder8\jdk1.4\bin\javaw -classpath "C:\JBuilder8\thirdparty\jakarta-tomcat-4.0.6-LE-jdk14\bin\bootstrap.jar;C:\JBuilder8\jdk1.4\lib\tools.jar"  -Dcatalina.home="C:/JBuilder8/thirdparty/jakarta-tomcat-4.0.6-LE-jdk14"  org.apache.catalina.startup.Bootstrap -config "C:\Documents and Settings\Faye\jbproject\system\Tomcat\conf\server8080.xml" start 
HttpConnector Opening server socket on all host IP addressesStarting service Tomcat-StandaloneApache Tomcat/4.0.6WebappLoader[]: Deploying class repositories to work directory C:\Documents and Settings\Faye\jbproject\system\Tomcat\workWebappLoader[]: Deploy JAR /WEB-INF/lib/mssqlserver.jar to C:\Documents and Settings\Faye\jbproject\system\defaultroot\WEB-INF\lib\mssqlserver.jarWebappLoader[]: Reloading checks are enabled for this ContextStandardManager[]: Seeding random number generator class java.security.SecureRandomStandardManager[]: Seeding of random number generator has been completedContextConfig[]: Added certificates -> request attribute ValveStandardWrapper[:default]: Loading container servlet defaultStandardWrapper[:invoker]: Loading container servlet invokerHttpConnector[8080] Starting background threadStandardWrapperValve[debugjsp]: Servlet.service() for servlet debugjsp threw exceptionjava.lang.NullPointerExceptionjava.lang.NullPointerException at org.apache.jsp.login$jsp._jspService(login$jsp.java:100) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:201) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2347) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1027) at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1125) at java.lang.Thread.run(Thread.java:536)

Answer 1

Apache Tomcat/4.0.6 - HTTP Status 500 - Internal Server Error
type Exception report
message Internal Server Error
description The server encountered an internal error (Internal Server Error) that prevented it from fulfilling this request.
exception java.lang.NullPointerException
 
at org.apache.jsp.login$jsp._jspService(login$jsp.java:104)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:201)
 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381)
 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
 at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
 at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
 at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
 at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2347)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
 at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
 at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
 at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
 at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
 at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1027)
 at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1125)
 at java.lang.Thread.run(Thread.java:536)

Answer 2

//login.htm
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>登陆页面</title>
</head>
<body>
<CENTER>
<FONT SIZE=5 COLOR=BLUE>
用户登陆
</FONT>
</CENTER>
<HR>
<P></P>
<FORM action="login.jsp" method="post" name="form1">
  <P align="center">用户名：
    <INPUT name="user" type="text" value="bbb">
  </P>
  <P align="center"> 密码：
    <INPUT name="pwd" type="password" value="bbb">
  </P>
  <div align="center">
    <INPUT type="submit" value="登陆" name=submit1 >
    <INPUT type="reset" value="取消" name=reset1>
  </div></FORM>
<p align="center">&nbsp;</p>
<p align="center">&nbsp;</p>
<p align="center">copyright&copy;2003  Lancelot</p>
</BODY>
</HTML>//login.jsp
<%@ page contentType="text/html; charset=GBK" %>
<%@ page import="java.sql.*"%>
<html>
<head>
<title>
login
</title>
</head>
<body bgcolor="#ffffff">
<jsp:useBean id="login" scope="application" class="JavaBean.login"/>
<jsp:setProperty name="login" property="*"/>
<%
String user=request.getParameter("user").trim();
String sql="select * from admin";
ResultSet rs=login.executeQuery(sql);
if(!rs.next())
{
out.print("没有这个用户!");
%>
<a href="login.htm">返回</a>
<%
}
else
 {
        //设置user的Session
//session.setAttribute("user_name",user);
session.setAttribute("user_login","yes");
response.sendRedirect("preserve.htm");
}
%>
</body>
</html>
//login.java
package JavaBean;
import java.sql.*;
import java.lang.*;
public class login {
  private Connection conn=null;//数据库连接对象
  private Statement stmt=null; //SQL语句对象
  String url="jdbc:odbc:xihua";//数据库连接字符串,new是数据源
  ResultSet rs=null;
  private String name;
  private String pwd;
  public login() {
  try{
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
    }
    catch(java.lang.ClassNotFoundException e){
          System.err.println("ERROR:"+e.getMessage());
              }
      }
  public void setName(String name){
    this.name=name;
  }
  public void setPwd(String pwd){
    this.pwd=pwd;
  }
  public String getName(){
    return this.name;
  }
  public String getPwd(){
    return this.pwd;
  }
   public ResultSet executeQuery(String sql){
                  rs=null;
                  try{
                  if(conn!=null)
                  conn.close();
                  conn=DriverManager.getConnection(url,name,pwd);
                  stmt=conn.createStatement();
                  rs=stmt.executeQuery(sql);
                      }
                      catch(SQLException ex){
               System.err.println("login.executeQuery:"+ex.getMessage());
                      }
                      return rs;
              }}
//preserve.htm
html>
<head><title>测试
</title>
</head>
<body>
<h1>测试</h1>
</body>
</html>
测试通过!

Answer 3

系统DSN改了,加了:sql="select * from admin"(事先建好的!)

Answer 4

login.executeQuery:[Microsoft][ODBC SQL Server Driver][SQL Server]对象名 'admin' 无效。
这是什么意思？怎么改？

Answer 5

admin是数据库中的一张表，你在你那改为相应的就可以了！