将二进制流转换为普通的字符串

         /// <summary>
        /// 二进制流转换为  普通字符串
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        public static string Decode(string s)
        {
            byte[] c = Convert.FromBase64String(s);
            return System.Text.Encoding.Default.GetString(c);

        }