jsp连接access问题

javabean代码：package db;import java.sql.*; //导入数据库操作的类

public class DBConnAccess { //构造方法，初始化
private Connection conn; //连接对象
    private Statement stmt; //语句对象
    private ResultSet rs; //结果集对象
    private String accessdriver; //保存Access驱动程序字符串
    private String accessURL; //保存Access连接字符串
    public DBConnAccess(){
        //Access驱动程序
        accessdriver = "sun.jdbc.odbc.JdbcOdbcDriver";
        //连接字符串
        accessURL = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=d:/shop.mdb";
        conn = null;
    }
    public Connection getConnToAccess(String dbpath){
        try{
            accessURL = accessURL + dbpath;
            Class.forName(accessdriver);
            conn = DriverManager.getConnection(accessURL);
        }catch(Exception e){
            System.out.println("操作数据库出错，请仔细检查");
            System.err.println(e.getMessage());
        }
        return conn;
    }

    //关闭数据库连接
    public void close(){
        try{
            //rs.close();
            //stmt.close();
            conn.close();
        }catch(SQLException sqlexception){
            sqlexception.printStackTrace();
        }
    }
}jsp代码：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" import="java.sql.*"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ page import ="db.DBConnAccess" %>
<jsp:useBean id="DBConn" scope="page" class="db.DBConnAccess"/>
<%
   //连接Accesss数据库
   String dbpath = "d:/shop.mdb"; //
   Connection conn = DBConn.getConnToAccess(application.getRealPath(dbpath));
   Statement stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
   String sql = "select * from USER order by uid";
   
   ResultSet rs = stmt.executeQuery(sql);
   while (rs.next()) {
       out.print("用户名：");
       out.print(rs.getString("uid") + " 密码：");
       out.print(rs.getString("pwd") + "<br>");
   }
   DBConn.close();
%>错误信息：
org.apache.jasper.JasperException: An exception occurred processing JSP page /view/checkInput.jsp at line 96:    //连接Accesss数据库
7:    String dbpath = "d:/shop.mdb"; //
8:    Connection conn = DBConn.getConnToAccess(application.getRealPath(dbpath));
9:    Statement stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
10:    String sql = "select * from USER order by uid";
11:    
12:    ResultSet rs = stmt.executeQuery(sql);
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:567)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:471)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
原因 java.lang.NullPointerException
org.apache.jsp.view.checkInput_jsp._jspService(checkInput_jsp.java:79)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)请高手指教 哪里错了 谢谢