如何获取 HttpRuntime.Cache 对象的到期日期时间? [英] How can I get the expiry datetime of an HttpRuntime.Cache object?

问题描述

是否可以获取 HttpRuntime.Cache 对象的到期时间 DateTime?

Is it possible to get the expiry DateTime of an HttpRuntime.Cache object?

如果是这样，最好的方法是什么?

If so, what would be the best approach?

推荐答案

我刚刚通过了反射器中的 System.Web.Caching.Cache.似乎所有涉及到期日期的内容都标记为内部.我发现唯一可以公开访问它的地方是通过 Cache.Add 和 Cache.Insert 方法.

I just went through the System.Web.Caching.Cache in reflector. It seems like everything that involves the expiry date is marked as internal. The only place i found public access to it, was through the Cache.Add and Cache.Insert methods.

所以看起来你运气不好，除非你想通过反思，除非你真的需要那个日期，否则我不建议这样做.

So it looks like you are out of luck, unless you want to go through reflection, which I wouldn't recommend unless you really really need that date.

但是如果您无论如何都想这样做，那么这里有一些代码可以解决问题:

But if you wish to do it anyway, then here is some code that would do the trick:

private DateTime GetCacheUtcExpiryDateTime(string cacheKey)
{
    object cacheEntry = Cache.GetType().GetMethod("Get", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(Cache, new object[] { cacheKey, 1 });
    PropertyInfo utcExpiresProperty = cacheEntry.GetType().GetProperty("UtcExpires", BindingFlags.NonPublic | BindingFlags.Instance);
    DateTime utcExpiresValue = (DateTime)utcExpiresProperty.GetValue(cacheEntry, null);

    return utcExpiresValue;
}

自 .NET 4.5 起 的内部公共 getterHttpRuntime.Cache 被替换为静态变量，因此您需要调用/获取静态变量:

Since .NET 4.5 the internal public getter of the HttpRuntime.Cache was replaced with a static variant and thus you will need to invoke/get the static variant:

object cacheEntry = Cache.GetType().GetMethod("Get").Invoke(null, new object[] { cacheKey, 1 });

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