.NetCore MemoryCache使用详解

services.AddMemoryCache(options => {
                // 缓存最大为100份
                //##注意netcore中的缓存是没有单位的，缓存项和缓存的相对关系
                options.SizeLimit = 2;
                //缓存满了时候压缩20%的优先级较低的数据
                options.CompactionPercentage = 0.2;
                //两秒钟查找一次过期项
                options.ExpirationScanFrequency = TimeSpan.FromSeconds(2);
            });

public bool Add(string key, object value, int ExpirtionTime = 20)
        {
            if (!string.IsNullOrEmpty(key))
            {
                MemoryCacheEntryOptions cacheEntityOps = new MemoryCacheEntryOptions()
                {
                    //滑动过期时间 20秒没有访问则清除
                    SlidingExpiration = TimeSpan.FromSeconds(ExpirtionTime),
                    //设置份数
                    Size = 1,
                    //优先级
                    Priority = CacheItemPriority.Low,
                };
                //过期回掉
                cacheEntityOps.ReGISterPostEvictionCallback((keyInfo, valueInfo, reason, state) =>
                {
                    Console.WriteLine($"回调函数输出【键:{keyInfo},值:{valueInfo},被清除的原因:{reason}】");
                });
                _cache.Set(key, value, cacheEntityOps);
            }
            return true;
        }

public interface ICacheService
    {
        /// <summary>
        ///  新增
        /// </summary>
        /// <param name="key"></param>
        /// <param name="value"></param>
        /// <param name="ExpirtionTime"></param>
        /// <returns></returns>
        bool Add(string key, object value, int ExpirtionTime = 20);
        /// <summary>
        /// 获取
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        string GetValue(string key);
        /// <summary>
        /// 验证缓存项是否存在
        /// </summary>
        /// <param name="key">缓存Key</param>
        /// <returns></returns>
        bool Exists(string key);
        /// <summary>
        /// 移除
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        bool Remove(string key);
    }

/// <summary>
    /// 缓存接口实现
    /// </summary>
    public class MemoryCacheService : ICacheService
    {
        protected IMemoryCache _cache;
        public MemoryCacheService(IMemoryCache cache)
        {
            _cache = cache;
        }
        public bool Add(string key, object value, int ExpirtionTime = 20)
        {
            if (!string.IsNullOrEmpty(key))
            {
                MemoryCacheEntryOptions cacheEntityOps = new MemoryCacheEntryOptions()
                {
                    //滑动过期时间 20秒没有访问则清除
                    SlidingExpiration = TimeSpan.FromSeconds(ExpirtionTime),
                    //设置份数
                    Size = 1,
                    //优先级
                    Priority = CacheItemPriority.Low,
                };
                //过期回掉
                cacheEntityOps.RegisterPostEvictionCallback((keyInfo, valueInfo, reason, state) =>
                {
                    Console.WriteLine($"回调函数输出【键:{keyInfo},值:{valueInfo},被清除的原因:{reason}】");
                });
                _cache.Set(key, value, cacheEntityOps);
            }
            return true;
        }
        public bool Remove(string key)
        {
            if (string.IsNullOrEmpty(key))
            {
                return false;
            }
            if (Exists(key))
            {
                _cache.Remove(key);
                return true;
            }
            return false;
        }
        public string GetValue(string key)
        {
            if (string.IsNullOrEmpty(key))
            {
                return null;
            }
            if (Exists(key))
            {
                return _cache.Get(key).ToString();
            }
            return null;
        }
        public bool Exists(string key)
        {
            if (string.IsNullOrEmpty(key))
            {
                return false;
            }
            object cache;
            return _cache.TryGetValue(key, out cache);
        }
    }