c#缓存帮助类

public static class CacheHelper
    {
        static object _lockObj = new object();

        private static Dictionary<string, object> _lockObjDict = new Dictionary<string, object>();

        /// <summary>
        /// 获取缓存,如果缓存不存在,则从 acquire 里获取
        /// 但是如果 acquire 得到的是 null,则不保存入缓存
        /// </summary>
        /// <typeparam name="TResult">缓存类型</typeparam>
        /// <param name="cacheProvider">缓存Provider</param>
        /// <param name="key">缓存Key</param>
        /// <param name="second">缓存时间</param>
        /// <param name="acquire">acquire</param>
        /// <returns>null或者缓存实例</returns>
        public static TResult GetBySeconds<TResult>(
              this ICacheProvider cacheProvider,
              string key,
              int second,
              Func<TResult> acquire)
        {
            ////缓存key不能为空,但是可以为空字符串
            if (key == null)
            {
                throw new ArgumentNullException("参数key不能为空");
            }

if (!_lockObjDict.ContainsKey(key))
                {
            lock (_lockObj)
            {
                if (!_lockObjDict.ContainsKey(key))
                {
                    _lockObjDict.Add(key, new object());
                }
            }
}

            ////如果当前缓存存在则直接返回
            if (cacheProvider.IsSet(key))
            {
                return cacheProvider.Get<TResult>(key);
            }

            lock (_lockObjDict[key])
            {
                //再次检测当前缓存存在则直接返回
                if (cacheProvider.IsSet(key))
                {
                    return cacheProvider.Get<TResult>(key);
                }

                ////如果不存在则调用获取方法
                var result = acquire();
                ////如果获取到的结果为空,则不缓存
                if (result != null)
                {
                    cacheProvider.Set(key, result, second);
                }

                return result;
            }
        }
    }