数据缓存流程

 //查询Redis
    String key="dish_"+categoryId;
    //存在返回
    List<DishVO> list = (List<DishVO>) redisTemplate.opsForValue().get(key);
    if (list!=null&&list.size()>0){
        return Result.success(list);
    }
    //不存在查询数据库，放入Redis
    Dish dish = new Dish();
    dish.setCategoryId(categoryId);
    dish.setStatus(StatusConstant.ENABLE);//查询起售中的菜品

    list = dishService.listWithFlavor(dish);
    redisTemplate.opsForValue().set(key,list);

    return Result.success(list);
}