1.方式一：手動位移

     /// <summary>
        /// int轉byte
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static byte[] intToBytes(int value)
        {
            byte[] src = new byte[4];
            src[3] = (byte)((value >> 24) & 0xFF);
            src[2] = (byte)((value >> 16) & 0xFF);
            src[1] = (byte)((value >> 8) & 0xFF);
            src[0] = (byte)(value & 0xFF);
            return src;
        }
        /// <summary>
        /// byte轉int
        /// </summary>
        /// <param name="src"></param>
        /// <param name="offset"></param>
        /// <returns></returns>
        public static int bytesToInt(byte[] src, int offset)
        {
            int value;
            value = (int)((src[offset] & 0xFF)
                    | ((src[offset + 1] & 0xFF) << 8)
                    | ((src[offset + 2] & 0xFF) << 16)
                    | ((src[offset + 3] & 0xFF) << 24));
            return value;
        }  
2.方式二：使用BitConverter

 /// <summary>
        /// 數字和位元組之間互轉
        /// </summary>
        /// <param name="num"></param>
        /// <returns></returns>
        public static int IntToBitConverter(int num)
        {
            int temp = 0;
            byte[] bytes = BitConverter.GetBytes(num);//將int32轉換為位元組陣列
            temp = BitConverter.ToInt32(bytes, 0);//將位元組陣列內容再轉成int32型別
            return temp;
        }