.net 缓存之文件缓存依赖

CaCheHelp 类中代码如下：

#region 根据键从缓存中读取保持的数据
        /// <summary>
        /// 根据键从缓存中读取保持的数据
        /// </summary>
        /// <param name="CaCheKey">索引键值</param>
        /// <returns></returns>
        public static object GetCaChe(string CaCheKey)
        {
            System.Web.Caching.Cache ca = HttpRuntime.Cache;
            return ca[CaCheKey];
        }
        #endregion

        #region 设置当前应用程序中指定的缓存项  重载  设置依赖项
        /// <summary>
        /// 设置当前应用程序中指定的缓存项  重载  设置依赖项
        /// </summary>
        /// <param name="CaCheKey">索引键值</param>
        /// <param name="objValue">缓存对象</param>
        /// <param name="dep">依赖对象</param>
        public static void SetCaChe(string CaCheKey, object objValue, System.Web.Caching.CacheDependency dep)
        {
            System.Web.Caching.Cache ca = HttpRuntime.Cache;
            ca.Insert(CaCheKey, objValue, dep,System.Web.Caching.Cache.NoAbsoluteExpiration,System.Web.Caching.Cache.NoSlidingExpiration, System.Web.Caching.CacheItemPriority.Default,null);
        } 
        #endregion

页面调用：

string CaCheKey = "cachekey";
            object objModel = CaCheHelp.GetCaChe(CaCheKey);
            
            if (objModel == null)
            {
                objModel = DateTime.Now;
                if (objModel != null)
                {
                    System.Web.Caching.CacheDependency dep = new System.Web.Caching.CacheDependency("D:\CacheTest.txt");//依赖D盘下CacheTest.txt内容改变时更新缓存
                    CaCheHelp.SetCaChe(CaCheKey, objModel, dep);
                }

            }
            
            lable_time.InnerText = objModel.ToString();