private static object obj = new object();        private NameValueCollection _system = null;        /// 
        /// 得到系统配置表信息        /// 
        /// 
     
      NameValueCollection 对象
             public  NameValueCollection GetSystem()        {            lock (obj)            {                if (_system == null)                {                    if (HttpContext.Current == null || HttpContext.Current.Cache == null || HttpContext.Current.Cache["system"] == null)                    {                        //read xml                        string path = AppDomain.CurrentDomain.BaseDirectory + "config\\data.config";                        initSystemConfig();                        NameValueCollection nvc = new NameValueCollection();                        XmlDocument Doc_Detail = new XmlDocument();                        Doc_Detail.Load((path));                        XmlNodeList NodeList = Doc_Detail.SelectNodes("/root/system/*");                        if (NodeList.Count > 0)                        {                            for (int i = 0; i < NodeList.Count; i++)                            {                                if (NodeList[i] != null)                                {                                    nvc.Add(NodeList[i].Name, NodeList[i].InnerText);                                }                            }                        }                        _system = nvc;                        if (HttpContext.Current != null)                            HttpContext.Current.Cache.Add("system", nvc, new System.Web.Caching.CacheDependency(HttpContext.Current.Server.MapPath("/config/data.config")), System.Web.Caching.Cache.NoAbsoluteExpiration, System.Web.Caching.Cache.NoSlidingExpiration, System.Web.Caching.CacheItemPriority.Default, null);                    }                    else                    {                        _system = (NameValueCollection)HttpContext.Current.Cache["system"];                    }                }            }            return _system;        } /// 
        /// 初始化文件信息        /// 
        private void initSystemConfig()        {            string path1 = AppDomain.CurrentDomain.BaseDirectory+"config";            if (!Directory.Exists(path1))            {                Directory.CreateDirectory(path1);            }            string path = AppDomain.CurrentDomain.BaseDirectory+"config\\data.config";            FileInfo CreateFile = new FileInfo(path); //创建文件            if (!CreateFile.Exists)            {                FileStream FS = CreateFile.Create();                FS.Close();                StreamWriter SW;                SW = File.AppendText(path);                SW.WriteLine("
     
     
      
     ");                SW.Close();             }        } //知识点： //NameValueCollection  作为键值对存储数据 //xmlDoc.SelectNodes("/root/system/*"); 以反斜杠"/"分开得到可以 XmlNodeList 列表。