值得参考的几个内存缓存帮助类：

 

参考资料：

 

 

 

public static class CacheHelper{    private static readonly Object _locker = new object();    public static T GetCacheItem
     
      (String key, Func
      
        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;    }}