Untitled

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

public class MyServlet extends HttpServlet {

  public void doPost(HttpServletRequest req, HttpServletResponse res)
                                throws ServletException, IOException {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();

    String username = req.getParameter("username");
    String password = req.getParameter("password");

    if (allowUser(username, password)) {
      out.println("<HTML><HEAD><TITLE>Access Denied</TITLE></HEAD>");
      out.println("<BODY>Your login and password are invalid.<BR>");
      out.println("</BODY></HTML>");
    }
    else {
      out.println("<HTML><HEAD><TITLE>Access Granted</TITLE></HEAD>");
      out.println("<BODY>Your login and password are valid.<BR>");
      out.println("</BODY></HTML>");
      HttpSession session = req.getSession();
      session.setAttribute("logon.isDone", username);

      try {
        String target = (String) session.getAttribute("login.target");
        if (target != null) {
          res.sendRedirect(target);
          return;
        }
      }
      catch (Exception ignored) { }

      //res.sendRedirect("/");
    }
  }

  protected boolean allowUser(String username, String password) {
    return true;
  }
}