public static DataTable CacheTable(string strSql, string tableName, string cacheKey)
        {
            //检查缓存中是否存在该数据项;
            DataTable data = (DataTable)HttpRuntime.Cache[cacheKey];
            if (data == null)
            {
                AggregateCacheDependency dependency = new AggregateCacheDependency();

                dependency.Add(new SqlCacheDependency(DBUtility.ConnectionManager.GetInstance().CacheConnectionString, tableName));

                data = DBUtility.DBExecute.ExecuteDataTable(DBUtility.DBExecute.ConnectionString, strSql);

                HttpRuntime.Cache.Add(cacheKey, data, dependency, DateTime.Now.AddHours(10), Cache.NoSlidingExpiration, CacheItemPriority.High, null);
            }

            return data;
        }
请问下这段代码，主要是哪些知识点啊。。。。我书上没见到过啊。大侠们  求解啊