Redis-商品查询缓存02-添加商品类型缓存

@GetMapping("list")
  public Result queryTypeList() {
      return typeService.queryTypeList();
  }

/**
 *  服务实现类
 */
@Service
public class ShopTypeServiceImpl extends ServiceImpl<ShopTypeMapper, ShopType> implements IShopTypeService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Autowired
    private IShopTypeService shopTypeService;

    @Override
    public Result queryTypeList() {
        // 从 redis 中查询商品类别
        String shopTypeList = stringRedisTemplate.opsForValue().get(SHOP_TYPE_KEY);
        // 判断redis是否存在
        if (StrUtil.isNotBlank(shopTypeList)) {
            // 存在，直接返回
            List<ShopType> list = JSONUtil.toList(shopTypeList, ShopType.class);
            return Result.ok(list);
        }
        // redis中 不存在的情况
        List<ShopType> typeList = shopTypeService
                .query().orderByAsc("sort").list();
        if (typeList==null) {
            return Result.fail("店铺不存在！");
        }
        // 数据库中存在， 写入redis中
        stringRedisTemplate.opsForValue().set(SHOP_TYPE_KEY, JSONUtil.toJsonStr(typeList));
        stringRedisTemplate.expire(SHOP_TYPE_KEY, SHOP_TYPE_TTL, TimeUnit.MINUTES);
        return Result.ok(typeList);
    }
}