Typical approach of using the servlets as controllers.

• By Michael Minh Nguyen
• August 16, 2001

package com.scalablemultitier;

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

public class registerUserTypicalApproach extends HttpServlet
{
  private static final int MAX_FIRST_NAME_LENGTH_ALLOWED = 10;

  public void doPost (HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException
  {
    User user;
    user = registerUser (request, response);
    if (user != null)
    {
      request.getSession (true).setAttribute ("User", user);
      request.getRequestDispatcher ("registrationSuccessful.jsp").
        forward (request, response);
    }
    else
    {
      request.getRequestDispatcher ("registrationFailed.jsp").
        forward (request, response);
    }
  }

  private User registerUser (HttpServletRequest request, HttpServlet-Response response)
  {
    User user = null;
    int length;
    String firstName, middleInitial, lastName, email;

    // 1. retrieve user registration data from 'request' object
    firstName = request.getParameter ("firstName");
    middleInitial = request.getParameter ("middleInitial");
    lastName = request.getParameter ("lastName");
    email = request.getParameter ("email");

    // 2. check to see user data is valid. Sample code below is done
    // only for firstName.
    // Actual program would include code for middle Initial, last
   // name and eMail.
    if (firstName == null)
    {
      return null;
    }
    length = firstName.trim ().length();
    if (length < 1 || length > MAX_FIRST_NAME_LENGTH_ALLOWED)
    {
      return null;
    }
    // 3. Implement controller logic to create beans such as session
   // bean, EJBs, and
    // regular beans as needed to register the user.
    // 4. return User bean if successful. Return null if failed.
    return user;
  }
}