java三层架构（MVC)实现的在线图书销售系统。其中应用到工厂

				package accp.yyw.model.command;								/**				 * Title: BookShop				 * Description: 				 * Copyright: Copyright (c) 2005				 * Company: accp				 * @author yyw				 * @version 1.0				 */				import javax.servlet.*;				import javax.servlet.http.*;				import java.io.*;								public interface ICommand {								          public String execute(HttpServletRequest request) throws Exception;				}