package moreservlets; import java.io.*; import javax.servlet.*; import javax.servlet.http.*; import java.util.ArrayList; import moreservlets.*; /** Servlet that displays a list of items being ordered. * Accumulates them in an ArrayList with no attempt at * detecting repeated items. Used to demonstrate basic * session tracking. *

* Taken from More Servlets and JavaServer Pages * from Prentice Hall and Sun Microsystems Press, * http://www.moreservlets.com/. * © 2002 Marty Hall; may be freely used or adapted. */ public class ShowItems extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession session = request.getSession(true); ArrayList previousItems = (ArrayList)session.getAttribute("previousItems"); if (previousItems == null) { previousItems = new ArrayList(); session.setAttribute("previousItems", previousItems); } String newItem = request.getParameter("newItem"); response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Items Purchased"; out.println(ServletUtilities.headWithTitle(title) + "\n" + "

" + title + "

"); synchronized(previousItems) { if (newItem != null) { previousItems.add(newItem); } if (previousItems.size() == 0) { out.println("No items"); } else { out.println("

" + (String)previousItems.get(i)); } out.println("

"); } } out.println(""); } }