新鲜的大白菜

我的数据库不知道怎么回事，可以正常查找和备份什么的，就是连不上JSP，希望哪位大虾可以帮帮我，小弟在这里先谢谢了，这个是我的源代码

<%@page contentType="text/html;charset=GBK"%>
<%@page import="java.sql.*"%>

<%
 //1.加载 数据库 驱动
 String DBDriver = "com.microsoft.jdbc.sqlserver.SQLServerDriver";

 try
 {
  Class.forName(DBDriver);
 }
 catch(java.lang.ClassNotFoundException e)
 {
  out.println("ROOT/WEB-INF/lib下没有  驱动");
 }

 //2.建立连接
 Connection conn = null;
 String url = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=zgqcw";
 String user = "zgqcw";
 String password = "zgqcw";

 try
 {
        conn = DriverManager.getConnection(url,user,password);  
 }
     catch(SQLException e)
     {
   out.println("没连上");
 }

 //3.生成  sql表述执行对象----相当于：查询分析器
 Statement stmt = null;

 try
 {
        stmt = conn.createStatement();         
     }
     catch(SQLException e)
     {
   out.println("没有生成 SQL表述执行对象");
 }

 //4.执行SQL

 String sql="select changshang_id,changshang_ming   "
     +"   from dbo.cs_changshang";

 ResultSet rs=stmt.executeQuery(sql);

 while(rs.next() ==true)
 {
%>
  <li>
  <%=rs.getInt("changshang_id")%>
  <%=rs.getString("changshang_ming")%>
<%
 }
%>

type Exception report

message

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

exception

org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

root cause

java.lang.NullPointerException
org.apache.jsp._11_jsp._jspService(org.apache.jsp._11_jsp:79)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.11 logs.

Apache Tomcat/5.5.11