HttpRuntime.Cache在ASP.NET的使用

一.缓存：

• 5个等级的缓存
1. 1级是网络级缓存，缓存在浏览器，CDN以及代理服务器中   （举个例子：每个帮助页面都进行了缓存，访问一个页面的代码非常简单）
2. 2级是由.net框架 HttpRuntime.Cache完成，在每台服务器的内存中。
3. 3级Redis,分布式内存键值存储，在多个支撑同一个站点的服务器上共享缓存项。
4. 4级SQL Server Cache，整个数据库，所有数据都被放到内存中。
5. 5级SSD。通常只在SQL Server预热后才生效

二.具体使用

        添加cachehelper类

 /// <summary>
    /// 缓存帮助类
    /// 时间：2016/05/07
    /// </summary>
    public class CacheHelper
    {
        #region 获取数据缓存

        /// <summary>
        /// 获取数据缓存
        /// </summary>
        /// <param name="cacheKey">键</param>
        /// <param name="objObject"></param>
        public static object GetCache(string cacheKey)
        {
            var objCache = HttpRuntime.Cache;
            return objCache[cacheKey];
        }
        #endregion

        #region 设置数据缓存
        /// <summary>
        /// 设置数据缓存
        /// </summary>
        public static void SetCache(string cacheKey, object objObject)
        {
            var objCache = HttpRuntime.Cache;
            objCache.Insert(cacheKey, objObject);
        }

        /// <summary>
        /// 设置数据缓存
        /// </summary>
        public static void SetCache(string cacheKey, object objObject, TimeSpan timeout)
        {
            var objCache = HttpRuntime.Cache;
            objCache.Insert(cacheKey, objObject, null, DateTime.MaxValue, timeout, CacheItemPriority.NotRemovable, null);
        }

        /// <summary>
        /// 设置数据缓存
        /// </summary>
        public static void SetCache(string cacheKey, object objObject, DateTime absoluteExpiration, TimeSpan slidingExpiration)
        {
            var objCache = HttpRuntime.Cache;
            objCache.Insert(cacheKey, objObject, null, absoluteExpiration, slidingExpiration);
        }
        #endregion

        #region 移除缓存
        /// <summary>
        /// 移除指定数据缓存
        /// </summary>
        public static void RemoveAllCache(string cacheKey)
        {
            var cache = HttpRuntime.Cache;
            cache.Remove(cacheKey);
        }

        /// <summary>
        /// 移除全部缓存
        /// </summary>
        public static void RemoveAllCache()
        {
            var cache = HttpRuntime.Cache;
            IDictionaryEnumerator cacheEnum = cache.GetEnumerator();
            while (cacheEnum.MoveNext())
            {
                cache.Remove(cacheEnum.Key.ToString());
            }
        }
        #endregion      
    }

       添加完对此进行调用先判断是否已经cache没有则添加

var cacheKey = "sid" + assessId + "uid" + studentId + "pindex" + pageHelper.PageIndex;
            var cachelist = CacheHelper.GetCache(cacheKey) as List<Question>;
            if (cachelist != null)
            {
                return cachelist;
            }
获取数据

    var result = GetAssessQuseList(pageHelper, tableName, fields, null, orderBy, true, studentId, otherFields);
            CacheHelper.SetCache(cacheKey, result, TimeSpan.FromSeconds(120));
            return result;

　　下面是移除cache

 var cacheKey = "sid" + assessId + "uid" + base.LoggingUser.UserId + "pindex" + pageIndex;
            var cachelist = CacheHelper.GetCache(cacheKey) as List<Question>;
            if (cachelist != null)
            {
                CacheHelper.RemoveAllCache(cacheKey);

            }