import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.io.*;
// This is a very simple servlet that keeps reads the "shopping cart"
// created for each user in a HttpSession object.
public class PurchaseServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
// Get the item and quantities entered
// Get the seesion object associated with this user (or create a new
// one if none exists)
HttpSession session = request.getSession();
// We can use the session to determine whether the user has
// skipped required stages to reach this point (possibly by
// typing in the URL to this point) by checking session
// attibutes which are set by previous required stages.
if (session.getAttribute("itemPurchased") == null) {
RequestDispatcher noPurchase =
request.getRequestDispatcher("Form");
noPurchase.forward(request, response);
return;
}
out.println("You have purchased:
");
out.println("| Item | Quantity |
");
Enumeration allItemNames = session.getAttributeNames();
while (allItemNames.hasMoreElements()) {
String itemName = (String)allItemNames.nextElement();
String itemQuantity = (String)session.getAttribute(itemName);
if (!itemName.equals("itemPurchased"))
out.println("| " + itemName + " | " + itemQuantity + " |
");
}
out.println("
");
// We can also use the session Id as a purchase order number.
// The response.encodeURL adds the session ID to the path if
// cookies cannot be used.
out.println("
Your order number is " + session.getId());
out.println("");
}
}