王者荣耀快速上分技巧:拜托给我看下这个是什么错误！怎么解决

JSP页面vote1.jsp
<%@ page contentType="text/html;charset=GB2312"%>
<%@ page import="lei.voteconn"%>
<%@ page import="java.sql.*"%>
<jsp:useBean id="vote" class="lei.voteconn" scope="page"/>
<% String rb=request.getParameter("type");
if(rb!=null && rb!="")
{
String sql="update vote set numb=numb+1 where id="+rb;
vote.executeQuery(sql);
}
%>
<jsp:forward page="view.jsp"/>

报错如下：
exception
org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:712)
org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:682)
org.apache.jsp.vote1_jsp._jspService(vote1_jsp.java:63)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)

root cause

java.lang.NullPointerException
org.apache.jsp.view_jsp._jspService(view_jsp.java:56)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:712)
org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:682)
org.apache.jsp.vote1_jsp._jspService(vote1_jsp.java:63)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
package lei;
import java.sql.*;
public class voteconn
{
Connection con;
ResultSet rs;
public voteconn()
{ try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e){
System.err.println(e.getMessage());
}
}
public ResultSet executeQuery(String sql)
{ try{con=DriverManager.getConnection("jdbc:odbc:research","","");
Statement stm=con.createStatement();
rs=stm.executeQuery(sql);
}
catch(SQLException ex){
System.err.println(ex.getMessage());
}
return rs;
}
public int executeUpdate(String sql)
{ int result=0;
try{con=DriverManager.getConnection("jdbc:odbc:research","","");
Statement stmt=con.createStatement();
result=stmt.executeUpdate(sql);
}
catch(SQLException ex){
System.err.println(ex.getMessage());
}
return result;
}
}