用MyEclipse Tomcat运行Statement stmt=conn.createStatement();出错怎么解决

问题遇到的现象和发生背景

应该是 Statement stmt=conn.createStatement();这句代码有错，但是不知道怎么改

用代码块功能插入代码，请勿粘贴截图

<%@ page language="java" import="java.sql.*" pageEncoding="UTF-8"%>
<jsp:useBean id="DBConn" class="conn.DBConnAccess" scope="request"/>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'checkuser.jsp' starting pagetitle>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    

  head>
  
  <body>
    <%
        request.setCharacterEncoding("utf-8");
        String username=request.getParameter("loginName");
        String password=request.getParameter("password");
        String checkcode=request.getParameter("checkcode");
        String piccode=request.getSession().getAttribute("piccode").toString();
        String role=request.getParameter("role");
        String dbpath=request.getRealPath("/")+"DB.accdb";
        Connection conn=DBConn.getConnToAccess(dbpath);
        Statement stmt=conn.createStatement();
        String sql="select * from userinfo";
        sql+="where loginname='"+username+"'and password='"+password+"' and role='"+role+"'";
         ResultSet rs=stmt.executeQuery(sql);
         if(checkcode.equals(piccode)&&rs.next())
         {
              session.setAttribute("userName",username);
              if(role.equals("admin"))
              {
              response.sendRedirect("admin/main.jsp");
              }
              else if(role.equals("client"))
              {
              response.sendRedirect("client/main.jsp");
              }
              }
         else{
             response.sendRedirect("login.jsp");
         }
 %>
     
  body>
html>

运行结果及报错内容

HTTP Status 500 -

type Exception report

message

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

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /checkUser.jsp at line 36

33: String role=request.getParameter("role");
34: String dbpath=request.getRealPath("/")+"DB.accdb";
35: Connection conn=DBConn.getConnToAccess(dbpath);
36: java.sql.Statement stmt=conn.createStatement();
37: String sql="select * from userinfo";
38: sql+="where loginname='"+username+"'and password='"+password+"' and role='"+role+"'";
39: ResultSet rs=stmt.executeQuery(sql);

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:524)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

root cause

java.lang.NullPointerException
org.apache.jsp.checkUser_jsp._jspService(checkUser_jsp.java:103)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.

Apache Tomcat/6.0.13

我的解答思路和尝试过的方法

将 Statement stmt=conn.createStatement(); 改为
java.sql.Statement stmt=conn.createStatement(); 但是还是不行【！我是用MyEclipse Tomcat运行的！】

我想要达到的结果

希望可以正常运行，谢谢大家

你这个拼接sql 最起码有个空格间隔吧
不然不就select * from userinfowhere了，直接报错

可能是34行 Connection conn=DBConn.getConnToAccess(dbpath);
没有换取到连接，conn对象为null.所以35行报了NullPointerException异常