import java.sql.*;


public class Validate
{

public static boolean checkUser(String email,String pass)

{
  boolean st =false;
  try{

 //loading drivers for mysql
     Class.forName("com.mysql.jdbc.Driver");

 //creating connection with the database
     Connection con=DriverManager.getConnection
                    ("jdbc:mysql:/ /localhost:3306/test","root","studytonight");
     PreparedStatement ps =con.prepareStatement
                         ("select * from register where email=? and pass=?");
     ps.setString(1, email);
     ps.setString(2, pass);
     ResultSet rs =ps.executeQuery();
     st = rs.next();

  }catch(Exception e)
  {
      e.printStackTrace();
  }
     return st;
  }
}

import java.io.*;
 import javax.servlet.*;
 import javax.servlet.http.*;
  import java.sql.*;

 public class Login extends HttpServlet
   {

     protected void doPost(HttpServletRequest request, HttpServletResponse
    response)
         throws ServletException, IOException {
       response.setContentType("text/html;charset=UTF-8");
       PrintWriter out = response.getWriter();

       String email = request.getParameter("email");
      String pass = request.getParameter("pass");

      if(**Validate**.checkUser(email, pass))
     {
        RequestDispatcher rs = request.getRequestDispatcher("Welcome");
        rs.forward(request, response);
    }
    else
    {
       out.println("Username or Password incorrect");
       RequestDispatcher rs = request.getRequestDispatcher("index.html");
          rs.include(request, response);
  }
  }