How to separate Business Logic from the servlet

I have made a simple login example which checks Userid & Password from a Microsoft Access Database...I put all the code in one servlet ...But now i want to put my Business Logic in a seperate java class....But i am unable to do it..

The code written by me is here:
This is the servlet:

package com.ducat.servlets;
import java.io.IOException;
import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.*;
import javax.servlet.http.*;

public class P extends HttpServlet {
    private static final String CONTENT_TYPE = "text/html; charset=windows-1252";

public void init(ServletConfig config) throws ServletException {
        super.init(config);
    }

public void doPost(HttpServletRequest request,
                       HttpServletResponse response) throws ServletException,
                                                            IOException {
        response.setContentType(CONTENT_TYPE);
        PrintWriter out = response.getWriter();
        try{
            
        String dataSourceName = "ddsn";
        String dbURL = "jdbc:odbc:" + dataSourceName;
        Connection con = DriverManager.getConnection(dbURL, "",""); 
        Statement s = con.createStatement();
        
        String name = request.getParameter("username"); 
        String password = request.getParameter("password");
        s.execute("select * from Table2 ");
        ResultSet rs = s.getResultSet();

if (rs != null) 
        while ( rs.next() )
        {
                if(
                        (!(name.equals ("null")) && name.equals(rs.getString ("username"))) && 
                                (!(password.equals ("null")) && password.equals(rs.getString ("password"))))
                {
                response.sendRedirect("m.html");
            }
            else{
                out.println("Invalid UserName or Password");
            }
        }   
        out.close();
    }
        catch(Exception e){
                 out.println(e);
        }
        }
}

and the two html pages made by me are:
(1)index.html

(2)M.html

and i put UserName & Password in database name DB2

BUT NOW I WANT TO PUT BUSINESS LOGIC IN A SEPERATE JAVA CLASS...
can anyone tell me the code how to do it...

Hi Shanu. Welcome to The Ranch! Your posts are much easier to read (and so more likely to get help) if you UseCodeTags. I've added them for you this time.

So write a business logic class that does not depend on the servlet environment. You can generalize the input to this class so that it can be tested as a standalone application,.

When you are sure it works right, your servlet can create an instance and use it - the "helper class" pattern.

For example, all of the POST input in the request can be gotten as a Map - write your helper class to use a Map as input.

See the javax.servlet.ServletRequest getParameterMap() method.

You can write your helper class with a main method so that it can be executed directly.

Bill

Hi

Check the MVC pattern , so you could invoke the methods of a third class from you servlet passing as the parametters the values of your request .

http://www.javaworld.com/javaworld/jw-12-1999/jw-12-ssj-jspmvc.html

Also you could code a class just to create the db connection and the db operations

Best regards