addfoodtocart.java

基于MVC架构实现的购物车功能

package com.lyh.web;

import java.io.IOException;
import java.io.PrintWriter;
import com.lyh.entity.*;
import java.util.*;
import java.io.*;
import java.text.*;
import javax.servlet.http.*;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AddFoodToCart extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=gbk");
		PrintWriter out = response.getWriter();
		
		
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=gbk");
		PrintWriter out = response.getWriter();
		
		//获得Session 
		HttpSession session=request.getSession(false);
		//定义转发器
		RequestDispatcher dispatcher;
		
		
		//从Session中取出购物车放入Map 对象中
		Map cart=(Map)session.getAttribute("cart");
		//从session 中取出当前要添加到购物车的餐品，放入FoodBean对象food中
		FoodBean  food=(FoodBean)session.getAttribute("foodToAdd");
		
		//如果购物车不存在。则构建购物车
		if(cart==null)
		{
			cart=new HashMap();
			//将购物车存入session中
			session.setAttribute("cart", cart);
		}
		//判断餐品是否在购物车中
		CartItemBean cartItem=(CartItemBean)cart.get(food.getFoodID());
		//如果餐品在购物车中，则更新其数量
		if(cartItem!=null)
		{
			cartItem.setQuantity(cartItem.getQuantity()+1);
			//否则，创将建一个条目到Map 中
			
		}else
		{
			cart.put(food.getFoodID(),new CartItemBean(food,1));
			//转向显示购物车
		}
		dispatcher=request.getRequestDispatcher("/ch05/shopCart.jsp");
		dispatcher.forward(request, response);
		
		
	}

}