public class CacheContainer
    {
        private static Hashtable ht = new Hashtable();

        /// <summary>
        /// objId :缓存id，objObject：缓存对象,expires:绝对过期时间
        /// </summary>
        /// <param name="objId"></param>
        /// <param name="objObject"></param>
        /// <param name="expires"></param>
        public void AddObject(string objId, object objObject, DateTime expires)
        {
            ContainerItem item = new ContainerItem() { Expires = expires, ObjObject = objObject };
            ht[objId] = item;
        }

        /// <summary>
        /// 默认缓存20分钟
        /// </summary>
        /// <param name="objId"></param>
        /// <param name="objObject"></param>
        public void AddObject(string objId, object objObject)
        {
            AddObject(objId, objObject, DateTime.Now.AddMinutes(20));
        }

        public object GetCacheObj(string objId)
        {
            object result = null;
            if (ht.Contains(objId))
            {
                var item = (ContainerItem)ht[objId];
                if (DateTime.Now<item.Expires)
                {
                    result =item.ObjObject;
                }
                else
                {
                    ht.Remove(objId);
                }
            }
            return result;
        }

        /// <summary>
        /// objId存在则删除，否则不处理
        /// </summary>
        /// <param name="objId"></param>
        public void RemoveObject(string objId)
        {
            if (ht.Contains(objId))
            {
                ht.Remove(objId);
            }
        }
    }

    public class ContainerItem
    {
        public object ObjObject { get; set; }
        public DateTime Expires { get; set; }
    }