16进制字符串转换为byte数组

/// <summary>

        /// 16进制字符转换为byte数组

        /// </summary>

        /// <param name="hexString">偶数位，由16进制字符[0-9a-fA-F]组成</param>

        /// <returns>null为转换失败</returns>

        private byte[] HexStringToBytes(string hexString)

        {

            if (string.IsNullOrEmpty(hexString))

                return null;



            int hexStringLength = hexString.Length;

            if (hexStringLength % 2 != 0)

                return null;

           

            Regex r = new Regex(@"[0-9a-fA-F]");

            if (!r.IsMatch(hexString))

                return null;



            int bufferLength = hexStringLength / 2;

            byte[] buffer = new byte[bufferLength];



            for (int i = 0; i < bufferLength; i++)

            {

                buffer[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16); //2个16进制字符转换为一个byte

            }



            return buffer;

        }