看了很多資料終于搞明白cache中absoluteExpiration，slidingExpiration這兩個參數的含義。

absoluteExpiration：用于設置絕對過期時間，它表示只要時間一到就過期，所以類型為System.DateTime，當給這個參數設置了一個時間時，slidingExpiration參數的值就只能為Cache.NoSlidingExpiration，否則出錯；

slidingExpiration：用于設置可調過期時間，它表示當離最后訪問超過某個時間段后就過期，所以類型為System.TimeSpan，當給這個參數設置了一個時間段時，absoluteExpiration的值就只能為Cache.NoAbsoluteExpiration，否則出錯；

???? 兩個使用實例

Cache.Add("name", content, null, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(10), System.Web.Caching.CacheItemPriority.Normal, null);

Cache.Add("name", content, null, DateTime.Now.AddMinutes(10), System.Web.Caching.Cache.NoSlidingExpiration, CacheItemPriority.Normal, null);

?

?

? //
??????? // 摘要:
??????? //???? Inserts an object into the System.Web.Caching.Cache object together with dependencies,
??????? //???? expiration policies, and a delegate that you can use to notify the application
??????? //???? before the item is removed from the cache.
??????? //
??????? // 參數:
??????? //?? key:
??????? //???? The cache key that is used to reference the object.
??????? //
??????? //?? value:
??????? //???? The object to insert into the cache.
??????? //
??????? //?? dependencies:
??????? //???? The file or cache key dependencies for the item. When any dependency changes,
??????? //???? the object becomes invalid and is removed from the cache. If there are no dependencies,
??????? //???? this parameter contains null.
??????? //
??????? //?? absoluteExpiration:
??????? //???? The time at which the inserted object expires and is removed from the cache.
??????? //???? To avoid possible issues with local time such as changes from standard time to
??????? //???? daylight saving time, use System.DateTime.UtcNow instead of System.DateTime.Now
??????? //???? for this parameter value. If you are using absolute expiration, the slidingExpiration
??????? //???? parameter must be set to System.Web.Caching.Cache.NoSlidingExpiration.
??????? //
??????? //?? slidingExpiration:
??????? //???? The interval between the time that the cached object was last accessed and the
??????? //???? time at which that object expires. If this value is the equivalent of 20 minutes,
??????? //???? the object will expire and be removed from the cache 20 minutes after it was
??????? //???? last accessed. If you are using sliding expiration, the absoluteExpiration parameter
??????? //???? must be set to System.Web.Caching.Cache.NoAbsoluteExpiration.
??????? //
??????? //?? onUpdateCallback:
??????? //???? A delegate that will be called before the object is removed from the cache. You
??????? //???? can use this to update the cached item and ensure that it is not removed from
??????? //???? the cache.
??????? //
??????? // 異常:
??????? //?? T:System.ArgumentNullException:
??????? //???? The key, value, or onUpdateCallback parameter is null.
??????? //
??????? //?? T:System.ArgumentOutOfRangeException:
??????? //???? You set the slidingExpiration parameter to less than TimeSpan.Zero or the equivalent
??????? //???? of more than one year.
??????? //
??????? //?? T:System.ArgumentException:
??????? //???? The absoluteExpiration and slidingExpiration parameters are both set for the
??????? //???? item you are trying to add to the Cache.-or-The dependencies parameter is null,
??????? //???? and the absoluteExpiration parameter is set to System.Web.Caching.Cache.NoAbsoluteExpiration,
??????? //???? and the slidingExpiration parameter is set to System.Web.Caching.Cache.NoSlidingExpiration.
??????? public void Insert(string key, object value, CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, CacheItemUpdateCallback onUpdateCallback);

轉載于:https://www.cnblogs.com/maijin/p/7049355.html

總結

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