购物车逻辑实现 Session缓存

package com.offcn.easybuy.controller;

import java.util.Date;
import java.util.List;
import javax.annotation.Resource;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import com.offcn.easybuy.mapper.ProductMapper;
import com.offcn.easybuy.pojo.Address;
import com.offcn.easybuy.pojo.CarItem;
import com.offcn.easybuy.pojo.Cart;
import com.offcn.easybuy.pojo.Order;
import com.offcn.easybuy.pojo.Product;
import com.offcn.easybuy.pojo.User;
import com.offcn.easybuy.service.IAddressService;
import com.offcn.easybuy.service.IOrderService;
import com.offcn.easybuy.service.IProductService;


@Controller
@RequestMapping("/car")
public class ShoppingCartController {
	@Resource
	private IProductService productService;
	@Resource
	private IAddressService addressService;
	@Resource
	private IOrderService orderService;
	
	//购物车
	@RequestMapping("/add")
	@ResponseBody
	public String add(int entityId,int quantity,HttpSession session) {
		//通过主键id找到具体商品
		Product product = productService.findProductById(entityId);
		//获取购物车值
		Cart cart = getCartFromSession(session);
		String carItem = cart.addCarItem(product, entityId, quantity);
		session.setAttribute("cart", cart);
		cart.calculateTotalPrice();
		return "添加成功";
	}
	
	//从购物车拿值
	public Cart getCartFromSession(HttpSession session) {
		
		Cart cart = (Cart)session.getAttribute("cart");
		if(cart==null) {
			cart=new Cart();
		}
		return cart;
	}
	
	//刷新购物车
	@RequestMapping("/reflush")
	public String reflush(HttpSession session) {
		return "/common/pre/searchBar";
	}
	
	//toSettlement界面用于加载settlement1页面
	@RequestMapping("/settlement")
	public String settlement1() {
		return "/pre/settlement/settlement1";
	}
	
	//修改购物车,加或者减，
	@RequestMapping("/modifyCart")
	@ResponseBody
	public String modCart(int entityId,int quantity,HttpSession session) {
		 int quantity1=0;
		 float price=0;
		Product product = productService.findProductById(entityId);
			Cart cart = getCartFromSession(session);
			//拿到购物车项的集合
			List<CarItem> list = cart.getItems();
			//遍历购物车项
			for (CarItem carItem : list) {
				if(carItem.getProduct().getId()==entityId) {
						//quantity1是修改后的数量
						quantity1=quantity;
						//对购物车项数量重新修改
						carItem.setQuantity(quantity1);
						//每一项的小计
						price=product.getPrice()*quantity1;
						//重新设置购物车项的小计
						carItem.setPrice(price);
						break;
				}
			}
			cart.calculateTotalPrice();
			//再次把购物车放到session
			session.setAttribute("cart", cart);		
			return "true";
	}
	
	//删除购物车项
	@RequestMapping("/removeCart")
	@ResponseBody
	public String removeCart(HttpSession session,int entityId) {
		Cart cart = getCartFromSession(session);
		List<CarItem> list = cart.getItems();
		for (int i = 0; i < list.size(); i++) {
			if(list.get(i).getProduct().getId()==entityId){
				list.remove(i);
			}
		}
		//调用计算总价的方法，删除每一项需要重新计算总价
		cart.calculateTotalPrice();
		//重新将购物车放置在session中，覆盖原来的购物车
		session.setAttribute("cart", cart);	
		return "true";
		
	}
	//用户sttlement2界面遍历旧地址
	@RequestMapping("/settlement2")
	public String toSettlement2(HttpSession session,Model model) {
		
				User user = (User)session.getAttribute("userSession");		
				//通过登录后用户的id查地址，用户的id可以从session中获取
				List<Address> addressList = addressService.findAddressByUserId(user.getId());
				model.addAttribute("userAddressList", addressList);
		return "/pre/settlement/settlement2";
	}
	
	//增加购物车的订单
	@RequestMapping("/addOrder")
	public String addCarOrder(HttpSession session,String newAddress,float cost) {
		
		User user = (User)session.getAttribute("userSession");
		
		Order order=new Order();
		//用户的id可以从session中获取
		order.setUserid(user.getId());
		order.setLoginname(user.getLoginName());
		order.setUseraddress(newAddress);
		order.setCreatetime(new Date());
		order.setCost(cost);
				
		orderService.insertSelective(order);
		
		//订单号是uuid，在sql语句自动生成,，
		String regex="-";
		String uuid= order.getSerialnumber();
		String uuid1 = uuid.replaceAll(regex, "");
		order.setSerialnumber(uuid1);
		//因为生成的uuid是有-的，要去掉只能重新修改
		orderService.updateByPrimaryKeySelective(order);
		
		session.setAttribute("currentOrder", order);
		
		return "/pre/settlement/settlement3";
		
		
	}
}

实体类：

package com.offcn.easybuy.pojo;

import java.util.ArrayList;
import java.util.List;

//购物车类
public class Cart {
	
	//购物车项集合
	private List<CarItem> items=new ArrayList<CarItem>();
	//总价钱
	private Double totalPrice;



	public List<CarItem> getItems() {
		return items;
	}

	public void setItems(List<CarItem> items) {
		this.items = items;
	}

	public Double getTotalPrice() {
		return totalPrice;
	}

	public void setTotalPrice(Double totalPrice) {
		this.totalPrice = totalPrice;
	}
	
	
	//添加方法
	public String addCarItem(Product product,int entityId,int quantity) {		
		int quantityAdd=0;
		//购物车项目如果是空的
		if(getItems().size()==0) {
			if(quantity>product.getStock()) {
				return "添加失败";
			}		
			//往购物车项集合里添加商品
			items.add(new CarItem(product,quantity));					
			//购物车项有内容
		}else if(getItems().size()>0) {
			//有购物车项内容，就开始遍历购物车项,
			String item=null;
			for (CarItem cart1 :getItems()){
				//如果存在相同的购物车项
				if(entityId==cart1.getProduct().getId()) {
				//quantityAdd原来的基础上增加,获得购物车项已有的数量+传进来增加的数量,
					quantityAdd=cart1.getQuantity()+quantity;
					item="1";
					if(quantityAdd>cart1.getProduct().getStock()) {
						return "添加失败";
					}					
					//重新赋值,
					cart1.setQuantity(quantityAdd);					
				}				
			}
			if(item==null) {
				if(quantity>product.getStock()){
					return "库存不足";
				}
				items.add(new CarItem(product,quantity));
			}
		}
		return "添加成功";
	}	
	
	//计算总价钱
	public double calculateTotalPrice() {
			//初始化总价
		   double totalPrice=0.0;	  
	        for(CarItem cart:getItems()){
	        	totalPrice=totalPrice+cart.getQuantity()*cart.getProduct().getPrice();      	
	        }
	        this.totalPrice=totalPrice;
	        
	        return totalPrice;
		
	}
	

}