cartwebimpl.java

一个优秀的供应商管理系统

package apusic.myshop.cart.web;


import javax.servlet.http.HttpSession;
import java.rmi.RemoteException;
import apusic.myshop.control.GeneralFailureException;

import apusic.myshop.control.web.ModelUpdateListener;
import apusic.myshop.control.web.ModelManager;
import apusic.myshop.cart.ejb.Cart;
import apusic.myshop.util.JNDINames;
import apusic.myshop.cart.model.CartModel;

public class CartWebImpl extends CartModel
  implements ModelUpdateListener {

  private ModelManager mm;
  private Cart cartEjb;

  public CartWebImpl() {
    super(null);
  }

  public void init(HttpSession session) {

	  // initializing super class with a null list. This means that
	  // if because of some bug, this object gets referenced
    // (typically in the JSP page) before performUpdate is called,
    // a null pointer exception will get thrown.
    this.mm = (ModelManager)session.getAttribute("modelManager");
    mm.addListener(JNDINames.CART_EJBHOME, this);
  }

  public void performUpdate() {
	  // Get data from the EJB
    if (cartEjb == null) {
      cartEjb = mm.getCartEJB();
    }
    try {
      copy(cartEjb.getDetails());
    } catch (RemoteException re) {
      throw new GeneralFailureException(re);
    }
  }
}