关于servlet

我新建一登陆界面userLogin.jsp
代码如下:
<%@ page contentType="text/html;charset=gb2312" %>
<html>
<head>
<title>用户登陆</title>
</head>
<body>
<div align="center"><p>用户登陆</p>
</div>
<br>
<div align="center">
<form name="form1" method="post" action="UserLogin">
<% if(request.getAttribute("errInf")!=null) {%>
<%= (String)request.getAttribute("errInf") %>
<%}%>
<p>帐号:<input name="id" type="text" id="id"></p>
<p>密码:<input name="password" type="password" id="password"></p>
<p><input type="submit" name="Submit" value="提交"></p>
</form>
</div>
</body>
</html>
用servlet UserLogin 处理 请求 代码如下:
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import bean.UserInf;
import bean.DBClass;
import bean.StrClass;
public class UserLogin extends HttpServlet{
public void doGet(HttpServletRequest request,HttpServletResponse response)
        throws ServletException,IOException{
HttpSession session=request.getSession();
String toJsp="/index.jsp";
if(session.getAttribute("userId")==null)
{
String id=request.getParameter("id");
String pwd=request.getParameter("password");
String query="select * from login where id="+"'"+id+"'"+"and pass="+"'"+pwd+"'";
DBClass db=new DBClass();
db.connect();
ResultSet result=db.executeQuery(query);
try{
if(result.next()){
session.setAttribute("userId",id);
toJsp="/index.jsp";
               }
else{
toJsp="userLogin.jsp";
request.setAttribute("errInf","*mi ma yu zhang hao bu pi pei*");
 }
}
catch(SQLException sqle){
System.err.println("error with connection:"+sqle);
}
       db.closeConnection();
                         
}


    request.getRequestDispatcher(toJsp).forward(request,response);

}
    public void doPost(HttpServletRequest request,HttpServletResponse response)
        throws ServletException,IOException{
                doGet(request,response);


  }

}DBClass 代码如下:
package bean;
import java.util.*;
import java.io.*;
import java.sql.*;
public class DBClass {
private String driver;
private String url;
private String username;
private String password;
private String message;
private Connection connection;
private Statement statement;
public DBClass()
{
driver="jdbc.odbc.JdbcOdbcDriver";
url="jdbc:odbc:soonf";
username="";
password="";
message="";
connection=null;
statement=null;}
public DBClass(String driver,String url,String username,String password)
{
this.driver=driver;
this.url=url;
this.password=password;
this.connection=null;
this.message="";
this.url=url;
this.username=username;
}
public String getDriver()
{
return this.driver;
}
public void setDriver(String driver)
{
   this.driver=driver;
}
public String getUrl()
{
   return this.url;
}
public void setUrl(String url)
{
  this.url=url;
}
public void setPassword(String password)
{
this.password=password;
}
public String getPassword()
{
return this.password;
}
public void setUsername(String username)
{
this.username=username;
}
public String getUsername()
{
return this.username;
}
public void setConnection(Connection connection)
{

this.connection=connection;
}
public void setStatement(Statement stat)
{
this.statement=statement;

}
public void setMessage(String message)
{
 this.message=message;
}public  Connection getConnection()
{

return this.connection;
}
public Statement getStatement()
{
return this.statement;

}
public  String setMessage()
{
 return this.message;
}
public void connect()
{
try{
Class.forName(driver);
connection=DriverManager.getConnection(url);
//connection=DriverManager.getConnection(url,username,password);
statement=connection.createStatement();

}catch(ClassNotFoundException cnfe){
message="connection :"+cnfe;

}catch(SQLException sqle){
message="executeQuery :"+sqle;
}
}
public ResultSet executeQuery(String query)
{
ResultSet resultset=null;
try{
resultset=statement.executeQuery(query);

}catch(SQLException sqle){
message="executeQuery:"+sqle;
}
return resultset;
}
public void executeUpdate(String command)
{try{
statement.executeUpdate(command);

}catch(SQLException sqle){
message="executeUpdate:"+sqle;
}

}public void closeConnection(){
try{
connection.close();
}catch(Exception e){
}
}
}可是运行的时侯提示:
type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception java.lang.NullPointerException
bean.DBClass.executeQuery(DBClass.java:114)
UserLogin.doGet(UserLogin.java:23)
UserLogin.doPost(UserLogin.java:49)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)