常用工具类 （创建调试日志、创建时间戳、随机字符串）

/// <summary>        /// 记录日志        /// </summary>        /// <param name="strMemo"></param>        public static void WriteLog(string strMemo)        {            string directoryPath = HttpContext.Current.Server.MapPath(@"\Logs");            string fileName = directoryPath + @"\log" + DateTime.Today.ToString("yyyyMMdd") + ".txt";            if (!Directory.Exists(directoryPath))                Directory.CreateDirectory(directoryPath);            StreamWriter sr = null;            try            {                if (!File.Exists(fileName))                {                    sr = File.CreateText(fileName);                }                else                {                    sr = File.AppendText(fileName);                }                sr.WriteLine(DateTime.Now + ": " + strMemo);            }            catch (Exception ex)            {            }            finally            {                if (sr != null)                    sr.Close();            }        }        /// <summary>        /// 返回一个八位的随机号，用于签名        /// </summary>        /// <returns></returns>        public static string randNonce()        {            var result = "";            var random = new Random((int)DateTime.Now.Ticks);            const string textArray = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";            for (var i = 0; i < 8; i++)            {                result = result + textArray.Substring(random.Next() % textArray.Length, 1);            }            return result;        }        /// <summary>        /// 时间戳的随机数        /// </summary>        /// <returns></returns>        public static string timeStamp()        {            DateTime dt1 = Convert.ToDateTime("1970-01-01 00:00:00");            TimeSpan ts = DateTime.Now - dt1;            return Math.Ceiling(ts.TotalSeconds).ToString();        }        /// <summary>        /// state 随机数        /// </summary>        /// <returns></returns>        public static string state()        {            Random ran = new Random();            int RandKey = ran.Next(100, 999);            return RandKey.ToString();        }