} else if (action.equals("ADD")) {
        //any previous buys of same cd?
        boolean match=false;
        CD aCD = getCD(req);
        if (buylist==null) {
          //add first cd to the cart
          buylist = new Vector(); //first order
          buylist.addElement(aCD);
        } else { // not first buy
          for (int i=0; i< buylist.size(); i++) {
            CD cd = (CD) buylist.elementAt(i);
            if (cd.getAlbum().equals(aCD.getAlbum())) {
              cd.setQuantity(cd.getQuantity()+aCD.getQuantity());
              buylist.setElementAt(cd,i);
              match = true;
            } //end of if name matches
          } // end of for
          if (!match)
            buylist.addElement(aCD);
        }
      }
      session.putValue("shopping.shoppingcart", buylist);
      String url="/jsp/shopping/EShop.jsp";
      ServletContext sc = getServletContext();
      RequestDispatcher rd = sc.getRequestDispatcher(url);
      rd.forward(req, res);
    } else if (action.equals("CHECKOUT"))  {
      float total =0;
      for (int i=0; i< buylist.size();i++) {
        CD anOrder = (CD) buylist.elementAt(i);
        float price= anOrder.getPrice();
        int qty = anOrder.getQuantity();
        total += (price * qty);
      }
      total += 0.005;
      String amount = new Float(total).toString();
      int n = amount.indexOf('.');
      amount = amount.substring(0,n+3);
      req.setAttribute("amount",amount);
      String url="/jsp/shopping/Checkout.jsp";
      ServletContext sc = getServletContext();
      RequestDispatcher rd = sc.getRequestDispatcher(url);
      rd.forward(req,res);
    }
  }
  private CD getCD(HttpServletRequest req) {
    //imagine if all this was in a scriptlet...ugly, eh?
    String myCd = req.getParameter("CD");
    String qty = req.getParameter("qty");
    StringTokenizer t = new StringTokenizer(myCd,"|");
    String album= t.nextToken();
    String artist = t.nextToken();
    String country = t.nextToken();
    String price = t.nextToken();
    price = price.replace('$',' ').trim();
    CD cd = new CD();
    cd.setAlbum(album);
    cd.setArtist(artist);
    cd.setCountry(country);
    cd.setPrice((new Float(price)).floatValue());
    cd.setQuantity((new Integer(qty)).intValue());
    return cd;
  }
}
每次页面中加入一个商品的时候，请求就会被发哦那个到这个控制器的servlets，这个servlets轮流的对每个动作作出决定，他们处理了被加入的商品的请求阐述，他实例化了一个代表所选择vcd的cdbean，并且更新了购物车之中的记录；