using System;
using System.Web;
using System.Web.Caching;

namespace NGuestBook.Utility
{
    /// <summary>
    /// 用于緩存操作
    /// </summary>
    public sealed class CacheAccess
    {
        /// <summary>
        /// 將對象加入到緩存中
        /// </summary>
        /// <param name="cacheKey">緩存鍵</param>
        /// <param name="cacheObject">緩存對象</param>
        /// <param name="dependency">緩存依賴項</param>
        public static void SaveToCache(string cacheKey, object cacheObject, CacheDependency dependency)
        {
            Cache cache = HttpRuntime.Cache;
            cache.Insert(cacheKey, cacheObject, dependency);
        }

        /// <summary>
        /// 從緩存中取得對象，不存在則返回null
        /// </summary>
        /// <param name="cacheKey">緩存鍵</param>
        /// <returns>獲取的緩存對象</returns>
        public static object GetFromCache(string cacheKey)
        {
            Cache cache = HttpRuntime.Cache;

            return cache[cacheKey];
        }
    }
}

保存和取緩存

using System;
using System.Configuration;
using System.Reflection;
using System.Web;
using System.Web.Caching;
using NGuestBook.Utility;

namespace NGuestBook.Factory
{
    /// <summary>
    /// 依賴注入提供者
    /// 使用反射機制實現
    /// </summary>
    public sealed class DependencyInjector
    {
        /// <summary>
        /// 取得數據訪問層對象
        /// 首先檢查緩存中是否存在，如果不存在，則利用反射機制返回對象
        /// </summary>
        /// <param name="className">數據訪問類名稱</param>
        /// <returns>數據訪問層對象</returns>
        public static object GetDALObject(string className)
        {
            /// <summary>
            /// 取得數據訪問層名稱，首先檢查緩存，不存在則到配置文件中讀取
            /// 緩存依賴項為Web.Config文件
            /// </summary>
            object dal = CacheAccess.GetFromCache("DAL");
            if (dal == null)
            {
                CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
                dal = ConfigurationManager.AppSettings["DAL"];
                CacheAccess.SaveToCache("DAL", dal, fileDependency);
            }

            /// <summary>
            /// 取得數據訪問層對象
            /// </summary>
            string dalName = (string)dal;
            string fullClassName = dalName + "." + className;
            object dalObject = CacheAccess.GetFromCache(className);
            if (dalObject == null)
            {
                CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
                dalObject = Assembly.Load(dalName).CreateInstance(fullClassName);
                CacheAccess.SaveToCache(className, dalObject, fileDependency);
            }

            return dalObject;
        }

        /// <summary>
        /// 取得業務邏輯層對象
        /// 首先檢查緩存中是否存在，如果不存在，則利用反射機制返回對象
        /// </summary>
        /// <param name="className">業務邏輯類名稱</param>
        /// <returns>業務邏輯層對象</returns>
        public static object GetBLLObject(string className)
        {
            /// <summary>
            /// 取得業務邏輯層名稱，首先檢查緩存，不存在則到配置文件中讀取
            /// 緩存依賴項為Web.Config文件
            /// </summary>
            object bll = CacheAccess.GetFromCache("BLL");
            if (bll == null)
            {
                CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
                bll = ConfigurationManager.AppSettings["BLL"];
                CacheAccess.SaveToCache("BLL", bll, fileDependency);
            }

            /// <summary>
            /// 取得業務邏輯層對象
            /// </summary>
            string bllName = (string)bll;
            string fullClassName = bllName + "." + className;
            object bllObject = CacheAccess.GetFromCache(className);
            if (bllObject == null)
            {
                CacheDependency fileDependency = new CacheDependency(HttpContext.Current.Server.MapPath("Web.Config"));
                bllObject = Assembly.Load(bllName).CreateInstance(fullClassName);
                CacheAccess.SaveToCache(className, bllObject, fileDependency);
            }

            return bllObject;
        }
    }
}