取得檔案的MD5值，可以用來判斷檔案是否已變更！

        /// <summary>
        /// 取的檔案指紋
        /// </summary>
        /// <param name="FileRoute">檔案路徑</param>
        /// <returns>回傳MD5</returns>
        public string GetFileMD5(string FileRoute)
        {
            if (File.Exists(FileRoute))
            {
                string str = string.Empty;
                using (FileStream FS = new FileStream(FileRoute, FileMode.Open, FileAccess.Read))
                {
                    byte[] bytes = (new MD5CryptoServiceProvider()).ComputeHash(FS);
                    str = BitConverter.ToString(bytes).Replace("-", string.Empty);
                    FS.Close();
                }
                return str;
            }
            else
                return string.Empty;
        }