Java代码模拟实现购物车

﹏ヽ暗。殇╰゛Y 2022-08-30 11:53 193阅读 0赞

相关博客：[https://hcshow.blog.csdn.net/article/details/119052399][https_hcshow.blog.csdn.net_article_details_119052399]

## 商品 ##

@Setter
    @Getter
    @AllArgsConstructor
    @NoArgsConstructor
    public class Goods { 
        private Integer id;
        private String name;
        private double price;
        private String imgs;
    
        @Override
        public boolean equals(Object o) { 
            if (this == o) { 
                return true;
            }
            if (o == null || getClass() != o.getClass()) { 
                return false;
            }
            Goods goods = (Goods) o;
            return Double.compare(goods.price, price) == 0 &&
                    Objects.equal(id, goods.id) &&
                    Objects.equal(name, goods.name) &&
                    Objects.equal(imgs, goods.imgs);
        }
    
        @Override
        public int hashCode() { 
            return Objects.hashCode(id, name, price, imgs);
        }
    }

**注**：通过重写equals和hashCode两个方法实现往Set中添加商品时，同一种商品在购物车中不被当作两个元素。

## 实现一： 使用Map<商品,购买数量> 表示商品（建议） ##

public class CartDemo{ 
        public static void main(String[] args) { 
            Map<Goods,Integer> cart = new HashMap<>();
            //第一次购买1号商品3个
            Goods key = new Goods(1,"honor",22,"honor.jpg");
            int amount =3;
            addGoods2Cart(cart, key, amount);
            //第二次购买1号商品4个
            key =new Goods(1,"honor",22,"honor.jpg");
            amount =4;
            addGoods2Cart(cart,key,amount);
            //第三次购买3号商品1个
            key =new Goods(3,"xiaomi",11,"xiaomi.jpg");
            amount =1;
            addGoods2Cart(cart,key,amount);
            cart.forEach((k,v)-> System.out.println(k+" : "+v));
        }
    
        private static void addGoods2Cart(Map<Goods, Integer> cart, Goods key, int amount) { 
            if(cart.containsKey(key)){ //如果新买商品已包含
               cart.put(key,cart.get(key)+amount) ;
            }else{ //未包含
                cart.put(key,amount);
            }
        }
    }

## 实现二 ：使用Map<商品编号,购买数量> 表示商品（不建议） ##

public static void main(String[] args) { 
            //商品的id 商品的数量
            Map<Integer, Integer> cart = new HashMap<>();
            //第一次购买1号商品3个
            cart.put(1, 4);
            //第二次购买1号商品4个
            cart.put(1, 3);
            //第三次购买3号商品1个
            cart.put(3, 1);
    
            //输出购物车中的内容
            cart.forEach((k,v)->{ 
                //从数据库中根据Goods的id，查询出Goods的详情
                Goods goods = new Goods(); //每次查看购物车都需要查询，效率不高
                goods.setId(k);
                System.out.println(goods +" : "+v);
            });
        }

[https_hcshow.blog.csdn.net_article_details_119052399]: https://hcshow.blog.csdn.net/article/details/119052399