背景：
1. 什么是MemoryCache？
memoryCache就是用电脑内存做缓存处理
2.使用范围？
可用于不常变的数据，进行保存在内存中，提高处理效率
代码：
/// <summary>
/// 基于MemoryCache的缓存辅助类
/// </summary>
public static class MemoryCacheHelper
{
private static readonly Object _locker = new object(); public static T GetCacheItem<T>(String key, Func<T> cachePopulate, TimeSpan? slidingExpiration = null, DateTime? absoluteExpiration = null)
{
if (String.IsNullOrWhiteSpace(key)) throw new ArgumentException("Invalid cache key");
if (cachePopulate == null) throw new ArgumentNullException("cachePopulate");
if (slidingExpiration == null && absoluteExpiration == null) throw new ArgumentException("Either a sliding expiration or absolute must be provided"); if (MemoryCache.Default[key] == null)
{
lock (_locker)
{
if (MemoryCache.Default[key] == null)
{
var item = new CacheItem(key, cachePopulate());
var policy = CreatePolicy(slidingExpiration, absoluteExpiration); MemoryCache.Default.Add(item, policy);
}
}
} return (T)MemoryCache.Default[key];
} private static CacheItemPolicy CreatePolicy(TimeSpan? slidingExpiration, DateTime? absoluteExpiration)
{
var policy = new CacheItemPolicy(); if (absoluteExpiration.HasValue)
{
policy.AbsoluteExpiration = absoluteExpiration.Value;
}
else if (slidingExpiration.HasValue)
{
policy.SlidingExpiration = slidingExpiration.Value;
} policy.Priority = CacheItemPriority.Default; return policy;
}
}