Servlet Problem

//AuthenticateDAO.java

package com.dao;
import java.sql.*;

public class AuthenticateDAO{
public static final String qry =
    "select count(*) from Studetail where uname = ? pwd =?" ;


    public static String validate(String un1 , String pass1){
         Connection con =null;
       PreparedStatement ps = null;
       ResultSet rs = null;
    try{
        //Register Driver And Establish the Connection
         Class.forName("oracle.jdbc.driver.OracleDriver");

        //Establish Connection
        con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","scott","tiger");

            ps = con.prepareStatement(qry);
            //set param
            ps.setString(1,un1);
            ps.setString(2,pass1);
System.out.println(qry);

        //Execute query
        rs = ps.executeQuery();

        //Process the resultset
        int cnt = 0;

        if(rs.next())
            cnt = rs.getInt(1);

        if(cnt==0)
            return "Invalid Credentials";
        else
            return "Valid Credentials";

    }//try
    catch(Exception e){
        e.printStackTrace();
        return "Internal Problem";
    }
    finally{
        try{
            if(rs!=null)
                rs.close();
        }catch(Exception e){
        e.printStackTrace();
        }

        try{
            if(ps!=null)
                ps.close();
        }catch(Exception e){
        e.printStackTrace();
        }

        try{
            if(con!=null)
                con.close();
        }catch(Exception e){
        e.printStackTrace();
        }

    }

    }//method
}//class
//;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
//LoginSrv.java
package com.nt;
import java . io.*;
import javax.servlet.*;
import javax . servlet.http.*;
import com.dao.AuthenticateDAO;

public class LoginSrv extends HttpServlet{
    public void doGet(HttpServletRequest req , HttpServletResponse res)
                throws IOException, ServletException{
        //General Setting
        PrintWriter pw = res.getWriter();
        res.setContentType("text/html");

        //read data from form
        String un =  req.getParameter("user");
        String pass =req.getParameter("pwd");

        //Use DAO class persistence logic
        String result = AuthenticateDAO.validate(un,pass);

        //Display Result
        pw.println("Result is ::" + result);

    //  pw.println(AuthenticateDAO.qry);

        //close the stream
        pw.close();

    }
}

//login.html
<form action = "loginurl">
Username : <input type = "text" name= "user"><br>
Password : <input type = "text" name = "pwd">
<input type = "submit" value = "Login">
</form>

//web.xml<web-app>
  <servlet>
    <servlet-name> abc </servlet-name>
    <servlet-class> com.nt.LoginSrv </servlet-class>
  </servlet>

   <servlet-mapping>
      <servlet-name> abc </servlet-name>
      <url-pattern> /loginurl </url-pattern>
   </servlet-mapping>
</web-app>