Point 2011-03-14

        public string MD5Encoding
        {
            get
            {
                using (FileStream fs = _fileInfo.OpenRead())
                {
                    byte[] btsHashValue = new MD5CryptoServiceProvider().ComputeHash(fs);
                    return BitConverter.ToString(btsHashValue).Replace("-", "");
                }
            }
        }

可以单独的设置一个DataTable的某一列为隐藏，是DataColumn的ColumnMapping属性。