public static string GetFileMD5(string FilePath)
        {
            try
            {
                FileStream get_file = new FileStream(FilePath, FileMode.Open, FileAccess.Read, FileShare.Read);
                System.Security.Cryptography.MD5CryptoServiceProvider get_md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
                byte[] hash_byte = get_md5.ComputeHash(get_file);
                string resule = System.BitConverter.ToString(hash_byte);
                resule = resule.Replace("-", "");
                get_file.Close();
                return resule;
            }
            catch
            {
                return string.Empty;
            }
        }