mall中购物车设计

该篇文章主要参考mall官方文档，并结合自己的使用感受做的一些笔记

1. 简介

无论是直接购买还是从添加到购物车，都要先经过购物车

2. 购物车流程

2.1 添加到购物车

1. 查询会员信息
2. 根据会员id,商品id和规格获取购物车中商品
3. 校验购物车中是否已存在该商品
   1. 不存在：直接新增
   2. 存在：在原有基础上新增数量

 @Override
    public int add(OmsCartItem cartItem) {
        int count;
        UmsMember currentMember =memberService.getCurrentMember();
        cartItem.setMemberId(currentMember.getId());
        cartItem.setMemberNickname(currentMember.getNickname());
        cartItem.setDeleteStatus(0);
        OmsCartItem existCartItem = getCartItem(cartItem);
        if (existCartItem == null) {
            cartItem.setCreateDate(new Date());
            count = cartItemMapper.insert(cartItem);
        } else {
            cartItem.setModifyDate(new Date());
            existCartItem.setQuantity(existCartItem.getQuantity() + cartItem.getQuantity());
            count = cartItemMapper.updateByPrimaryKey(existCartItem);
        }
        return count;
    }
    
      /**
     * 根据会员id,商品id和规格获取购物车中商品
     */
    private OmsCartItem getCartItem(OmsCartItem cartItem) {
        OmsCartItemExample example = new OmsCartItemExample();
        OmsCartItemExample.Criteria criteria = example.createCriteria().andMemberIdEqualTo(cartItem.getMemberId())
                .andProductIdEqualTo(cartItem.getProductId()).andDeleteStatusEqualTo(0);
        if (!StringUtils.isEmpty(cartItem.getProductSkuId())) {
            criteria.andProductSkuIdEqualTo(cartItem.getProductSkuId());
        }
        List<OmsCartItem> cartItemList = cartItemMapper.selectByExample(example);
        if (!CollectionUtils.isEmpty(cartItemList)) {
            return cartItemList.get(0);
        }
        return null;
    }

2.2 查询购物车列表

2.2.1 普通购物车列表

@Override
public List<OmsCartItem> list(Long memberId) {
    OmsCartItemExample example = new OmsCartItemExample();
    example.createCriteria().andDeleteStatusEqualTo(0).andMemberIdEqualTo(memberId);
    return cartItemMapper.selectByExample(example);
}

2.2.2 包含促销的购物车列表

 @Override
    public List<CartPromotionItem> listPromotion(Long memberId, List<Long> cartIds) {
        List<OmsCartItem> cartItemList = list(memberId);
        if(CollUtil.isNotEmpty(cartIds)){
            cartItemList = cartItemList.stream().filter(item->cartIds.contains(item.getId())).collect(Collectors.toList());
        }
        List<CartPromotionItem> cartPromotionItemList = new ArrayList<>();
        if(!CollectionUtils.isEmpty(cartItemList)){
            cartPromotionItemList = promotionService.calcCartPromotion(cartItemList);
        }
        return cartPromotionItemList;
    }

计算购物车促销活动

 @Override
    public List<CartPromotionItem> calcCartPromotion(List<OmsCartItem> cartItemList) {
        //1.先根据productId对CartItem进行分组，以spu为单位进行计算优惠
        Map<Long, List<OmsCartItem>> productCartMap = groupCartItemBySpu(cartItemList);
        //2.查询所有商品的优惠相关信息
        List<PromotionProduct> promotionProductList = getPromotionProductList(cartItemList);
        //3.根据商品促销类型计算商品促销优惠价格
        List<CartPromotionItem> cartPromotionItemList = new ArrayList<>();
        for (Map.Entry<Long, List<OmsCartItem>> entry : productCartMap.entrySet()) {
            Long productId = entry.getKey();
            PromotionProduct promotionProduct = getPromotionProductById(productId, promotionProductList);
            List<OmsCartItem> itemList = entry.getValue();
            Integer promotionType = promotionProduct.getPromotionType();
            if (promotionType == 1) {
                //单品促销
                for (OmsCartItem item : itemList) {
                    CartPromotionItem cartPromotionItem = new CartPromotionItem();
                    BeanUtils.copyProperties(item,cartPromotionItem);
                    cartPromotionItem.setPromotionMessage("单品促销");
                    //商品原价-促销价
                    PmsSkuStock skuStock = getOriginalPrice(promotionProduct, item.getProductSkuId());
                    BigDecimal originalPrice = skuStock.getPrice();
                    //单品促销使用原价
                    cartPromotionItem.setPrice(originalPrice);
                    cartPromotionItem.setReduceAmount(originalPrice.subtract(skuStock.getPromotionPrice()));
                    cartPromotionItem.setRealStock(skuStock.getStock()-skuStock.getLockStock());
                    cartPromotionItem.setIntegration(promotionProduct.getGiftPoint());
                    cartPromotionItem.setGrowth(promotionProduct.getGiftGrowth());
                    cartPromotionItemList.add(cartPromotionItem);
                }
            } else if (promotionType == 3) {
                //打折优惠
                int count = getCartItemCount(itemList);
                PmsProductLadder ladder = getProductLadder(count, promotionProduct.getProductLadderList());
                if(ladder!=null){
                    for (OmsCartItem item : itemList) {
                        CartPromotionItem cartPromotionItem = new CartPromotionItem();
                        BeanUtils.copyProperties(item,cartPromotionItem);
                        String message = getLadderPromotionMessage(ladder);
                        cartPromotionItem.setPromotionMessage(message);
                        //商品原价-折扣*商品原价
                        PmsSkuStock skuStock = getOriginalPrice(promotionProduct,item.getProductSkuId());
                        BigDecimal originalPrice = skuStock.getPrice();
                        BigDecimal reduceAmount = originalPrice.subtract(ladder.getDiscount().multiply(originalPrice));
                        cartPromotionItem.setReduceAmount(reduceAmount);
                        cartPromotionItem.setRealStock(skuStock.getStock()-skuStock.getLockStock());
                        cartPromotionItem.setIntegration(promotionProduct.getGiftPoint());
                        cartPromotionItem.setGrowth(promotionProduct.getGiftGrowth());
                        cartPromotionItemList.add(cartPromotionItem);
                    }
                }else{
                    handleNoReduce(cartPromotionItemList,itemList,promotionProduct);
                }
            } else if (promotionType == 4) {
                //满减
                BigDecimal totalAmount= getCartItemAmount(itemList,promotionProductList);
                PmsProductFullReduction fullReduction = getProductFullReduction(totalAmount,promotionProduct.getProductFullReductionList());
                if(fullReduction!=null){
                    for (OmsCartItem item : itemList) {
                        CartPromotionItem cartPromotionItem = new CartPromotionItem();
                        BeanUtils.copyProperties(item,cartPromotionItem);
                        String message = getFullReductionPromotionMessage(fullReduction);
                        cartPromotionItem.setPromotionMessage(message);
                        //(商品原价/总价)*满减金额
                        PmsSkuStock skuStock= getOriginalPrice(promotionProduct, item.getProductSkuId());
                        BigDecimal originalPrice = skuStock.getPrice();
                        BigDecimal reduceAmount = originalPrice.divide(totalAmount,RoundingMode.HALF_EVEN).multiply(fullReduction.getReducePrice());
                        cartPromotionItem.setReduceAmount(reduceAmount);
                        cartPromotionItem.setRealStock(skuStock.getStock()-skuStock.getLockStock());
                        cartPromotionItem.setIntegration(promotionProduct.getGiftPoint());
                        cartPromotionItem.setGrowth(promotionProduct.getGiftGrowth());
                        cartPromotionItemList.add(cartPromotionItem);
                    }
                }else{
                    handleNoReduce(cartPromotionItemList,itemList,promotionProduct);
                }
            } else {
                //无优惠
                handleNoReduce(cartPromotionItemList, itemList,promotionProduct);
            }
        }
        return cartPromotionItemList;
    }

2.3 更新购物车中商品的数量

 @Override
    public int updateQuantity(Long id, Long memberId, Integer quantity) {
        OmsCartItem cartItem = new OmsCartItem();
        cartItem.setQuantity(quantity);
        OmsCartItemExample example = new OmsCartItemExample();
        example.createCriteria().andDeleteStatusEqualTo(0)
                .andIdEqualTo(id).andMemberIdEqualTo(memberId);
        return cartItemMapper.updateByExampleSelective(cartItem, example);
    }

2.4 删除和清空购物车

删除和清空都是逻辑删除，这些数据我们都是非常宝贵的

@Override
    public int delete(Long memberId, List<Long> ids) {
        OmsCartItem record = new OmsCartItem();
        record.setDeleteStatus(1);
        OmsCartItemExample example = new OmsCartItemExample();
        example.createCriteria().andIdIn(ids).andMemberIdEqualTo(memberId);
        return cartItemMapper.updateByExampleSelective(record, example);
    }

@Override
    public int clear(Long memberId) {
        OmsCartItem record = new OmsCartItem();
        record.setDeleteStatus(1);
        OmsCartItemExample example = new OmsCartItemExample();
        example.createCriteria().andMemberIdEqualTo(memberId);
        return cartItemMapper.updateByExampleSelective(record,example);
    }