public void doGet(HttpServletRequest req, HttpServletResponse res)
      throws ServletException, IOException {

    res.setContentType("text/html");
    PrintWriter out = res.getWriter();
    Enumeration values = req.getParameterNames();
    String name = "";
    String value = "";
    String id = "";
    while (values.hasMoreElements()) {
      name = ((String) values.nextElement()).trim();
      value = req.getParameter(name).trim();
      if (name.equals("id")) id = value;
    }
    if (url.equals("")) {
      url = getServletContext().getInitParameter("url");
      cas_url = getServletContext().getInitParameter("cas_url");
    }
    HttpSession session = null;
    session = req.getSession(false);
    if (session != null) {
      session.invalidate();
    }
    res.sendRedirect(cas_url);
    return;
  }
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    boolean orderCompleted = true;

    // Get the user's session and shopping cart
    HttpSession session = request.getSession(true);
    ResourceBundle messages = (ResourceBundle) session.getAttribute("messages");
    ShoppingCart cart = (ShoppingCart) session.getAttribute("cart");

    if (cart == null) {
      cart = new ShoppingCart();
      session.setAttribute("cart", cart);
    }

    // Update the inventory
    try {
      utx.begin();
      bookDB.buyBooks(cart);
      utx.commit();
    } catch (Exception ex) {
      try {
        utx.rollback();
      } catch (Exception e) {
        System.out.println("Rollback failed: " + e.getMessage());
      }

      System.err.println(ex.getMessage());
      orderCompleted = false;
    }

    // Payment received -- invalidate the session
    session.invalidate();

    // set content type header before accessing the Writer
    response.setContentType("text/html");
    response.setBufferSize(8192);

    PrintWriter out = response.getWriter();

    // then write the response
    out.println(
        "<html>" + "<head><title>" + messages.getString("TitleReceipt") + "</title></head>");

    // Get the dispatcher; it gets the banner to the user
    RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/banner");

    if (dispatcher != null) {
      dispatcher.include(request, response);
    }

    if (orderCompleted) {
      out.println("<h3>" + messages.getString("ThankYou") + request.getParameter("cardname") + ".");
    } else {
      out.println("<h3>" + messages.getString("OrderError"));
    }

    out.println(
        "<p> &nbsp; <p><strong><a href=\""
            + response.encodeURL(request.getContextPath())
            + "/bookstore\">"
            + messages.getString("ContinueShopping")
            + "</a> &nbsp; &nbsp; &nbsp;"
            + "</body></html>");
    out.close();
  }