缓存滑动

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web;
using System.Web.Caching;

namespace WebCore.UI.Common
{
    public class Cache
    {
        private static System.Web.Caching.Cache _cache;
        static Cache()
        {
            HttpContext current = HttpContext.Current;
            if (current != null)
            {
                _cache = current.Cache;
            }
            else
            {
                _cache = HttpRuntime.Cache;
            }
        }

        private Cache()
        {
        }
        /// <summary>
        /// 清空
        /// </summary>
        public static void Clear()
        {
            IDictionaryEnumerator enumerator = _cache.GetEnumerator();
            ArrayList list = new ArrayList();
            while (enumerator.MoveNext())
            {
                list.Add(enumerator.Key);
            }
            foreach (string str in list)
            {
                _cache.Remove(str);
            }
        }
        /// <summary>
        /// 获取缓存
        /// </summary>
        /// <param name="key">key</param>
        /// <returns></returns>
        public static object Get(string key)
        {
            return _cache[key];
        }
        /// <summary>
        /// 移除缓存
        /// </summary>
        /// <param name="key"></param>
        public static void Remove(string key)
        {
            _cache.Remove(key);
        }
        public static void RemoveByPattern(string pattern)
        {
            IDictionaryEnumerator enumerator = _cache.GetEnumerator();
            Regex regex = new Regex(pattern, RegexOptions.Singleline | RegexOptions.Compiled | RegexOptions.IgnoreCase);
            while (enumerator.MoveNext())
            {
                if (regex.IsMatch(enumerator.Key.ToString()))
                {
                    _cache.Remove(enumerator.Key.ToString());
                }
            }
        }
        /// <summary>
        /// 固定过期时间
        /// </summary>
        /// <param name="key"></param>
        /// <param name="obj"></param>
        /// <param name="seconds"></param>
        /// <param name="dep"></param>
        /// <param name="absoluteExpiration">DateTime.Now</param>
        public static void Insert(string key, object obj, int seconds, CacheDependency dep, DateTime absoluteExpiration)
        {
            if (absoluteExpiration == null)
            {
                throw new NullReferenceException("AbsoluteExpiration不能为空");
            }
            if (seconds < 0)
            {
                throw new NullReferenceException("seconds 需大于0");
            }
            Insert(key, obj, dep, seconds, absoluteExpiration, null, CacheItemPriority.Default, null);
        }
        /// <summary>
        /// 滑动过期时间
        /// </summary>
        /// <param name="key"></param>
        /// <param name="obj"></param>
        /// <param name="seconds"></param>
        /// <param name="dep"></param>
        /// <param name="slidingExpiration">TimeSpan.FromMinutes(1)</param>
        public static void Insert(string key, object obj, CacheDependency dep, TimeSpan slidingExpiration)
        {
            if (slidingExpiration == null)
            {
                throw new NullReferenceException("SlidingExpiration不能为空");
            }
            Insert(key, obj, dep, 0, null, slidingExpiration, CacheItemPriority.Default, null);
        }
        public static void Insert(string key, object obj, CacheDependency dep, int seconds, DateTime? absoluteExpiration, TimeSpan? slidingExpiration, CacheItemPriority priority, CacheItemRemovedCallback cacheItemRemovedCallback)
        {
            if (string.IsNullOrEmpty(key))
            {
                throw new NullReferenceException("key 不能为空");
            }
            if (obj == null)
            {
                throw new NullReferenceException("obj 不能为空");
            }
            if (slidingExpiration.HasValue)
            {
                Insert(key, obj, dep, slidingExpiration.Value, priority, cacheItemRemovedCallback);
            }
            else
            {
                Insert(key, obj, dep, seconds, absoluteExpiration.Value, priority, cacheItemRemovedCallback);
            }
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="key"></param>
        /// <param name="obj"></param>
        /// <param name="dep"></param>
        /// <param name="seconds"></param>
        /// <param name="absoluteExpiration">absoluteExpiration.AddSeconds(seconds)</param>
        /// <param name="priority"></param>
        /// <param name="cacheItemRemovedCallback"></param>
        private static void Insert(string key, object obj, CacheDependency dep, int seconds, DateTime absoluteExpiration, CacheItemPriority priority, CacheItemRemovedCallback cacheItemRemovedCallback)
        {
            if (obj != null)
            {
                _cache.Insert(key, obj, dep, absoluteExpiration.AddSeconds(seconds), TimeSpan.Zero, priority, cacheItemRemovedCallback);
            }
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="key"></param>
        /// <param name="obj"></param>
        /// <param name="dep"></param>
        /// <param name="slidingExpiration">TimeSpan.FromMinutes(1)</param>
        /// <param name="priority"></param>
        /// <param name="cacheItemRemovedCallback"></param>
        private static void Insert(string key, object obj, CacheDependency dep, TimeSpan slidingExpiration, CacheItemPriority priority, CacheItemRemovedCallback cacheItemRemovedCallback)
        {
            if (obj != null)
            {
                _cache.Insert(key, obj, dep, System.Web.Caching.Cache.NoAbsoluteExpiration, slidingExpiration, priority, cacheItemRemovedCallback);
            }
        }
    }
}

 做了下网站栏目的服务器缓存，方法分两种，指定过期时间、滑动过期时间，方法不复杂。不是很完善，先记下来，以后再修补吧。
暂且记录几个不合理的地方：
（1）滑动缓存的时效 slidingExpiration 滑动 TimeSpan.FromMinutes(1) 一分钟

（2）absoluteExpiration  为了灵活，先传入 DateTime， 然后  DateTime.Now.AddSeconds。是以当前时间 N 秒后作为过期时间