基于Redis优化购物车 - 添加商品

@ApiOperation(value = "添加商品到购物车", notes = "添加商品到购物车", httpMethod = "POST")
@PostMapping("/add")
public JSONResult add(@RequestParam String userId,@RequestBody ShopcartBO shopcartBO,HttpServletRequest request,HttpServletResponse response
) {if (StringUtils.isBlank(userId)) {return JSONResult.errorMsg("");}System.out.println(shopcartBO);// 前端用户在登录的情况下，添加商品到购物车，会同时在后端同步购物车到redis缓存// 需要判断当前购物车中包含已经存在的商品，如果存在则累加购买数量String shopcartJson = redisOperator.get(FOODIE_SHOPCART + ":" + userId);List<ShopcartBO> shopcartList = null;if (StringUtils.isNotBlank(shopcartJson)) {// redis中已经有购物车了shopcartList = JsonUtils.jsonToList(shopcartJson, ShopcartBO.class);// 判断购物车中是否存在已有商品，如果有的话counts累加boolean isHaving = false;for (ShopcartBO sc: shopcartList) {String tmpSpecId = sc.getSpecId();if (tmpSpecId.equals(shopcartBO.getSpecId())) {sc.setBuyCounts(sc.getBuyCounts() + shopcartBO.getBuyCounts());isHaving = true;}}if (!isHaving) {shopcartList.add(shopcartBO);}} else {// redis中没有购物车shopcartList = new ArrayList<>();// 直接添加到购物车中shopcartList.add(shopcartBO);}// 覆盖现有redis中的购物车redisOperator.set(FOODIE_SHOPCART + ":" + userId, JsonUtils.objectToJson(shopcartList));return JSONResult.ok();
}

public static final String FOODIE_SHOPCART = "shopcart";

@ApiOperation(value = "获取商品子分类", notes = "获取商品子分类", httpMethod = "GET")
@GetMapping("/subCat/{rootCatId}")
public JSONResult subCat(@ApiParam(name = "rootCatId", value = "一级分类id", required = true)@PathVariable Integer rootCatId) {if (rootCatId == null) {return JSONResult.errorMsg("分类不存在");}List<CategoryVO> list = new ArrayList<>();String catsStr = redisOperator.get("subCat:" + rootCatId);if (StringUtils.isBlank(catsStr)) {list = categoryService.getSubCatList(rootCatId);/*** 查询的key在redis中不存在，* 对应的id在数据库也不存在，* 此时被非法用户进行攻击，大量的请求会直接打在db上，* 造成宕机，从而影响整个系统，* 这种现象称之为缓存穿透。* 解决方案：把空的数据也缓存起来，比如空字符串，空对象，空数组或list*/if (list != null && list.size() > 0) {redisOperator.set("subCat:" + rootCatId, JsonUtils.objectToJson(list));} else {redisOperator.set("subCat:" + rootCatId, JsonUtils.objectToJson(list), 5*60);}} else {list = JsonUtils.jsonToList(catsStr, CategoryVO.class);}//        List<CategoryVO> list = categoryService.getSubCatList(rootCatId);return JSONResult.ok(list);
}