關鍵代碼：

using System;using System.Text;namespace YanZhiwei.DotNet2.Utilities.Common{    /// <summary>    ///Random的幫助類    /// </summary>    public static class RandomHelper    {        #region 生成設置范圍內的Double的隨機數        /// <summary>        /// 生成設置范圍內的Double的隨機數        ///<para>eg:RandomHelper.NextDouble(1.5, 1.7);</para>         /// </summary>        /// <param name="miniDouble">生成隨機數的最大值</param>        /// <param name="maxiDouble">生成隨機數的最小值</param>        /// <returns>Double的隨機數</returns>        public static double NextDouble(double miniDouble, double maxiDouble)        {            Random _random = new Random((int)(DateTime.Now.Ticks));            return _random.NextDouble() * (maxiDouble - miniDouble) + miniDouble;        }        #endregion        #region 生成隨機字符串        /// <summary>        /// 生成隨機字符串        /// <para>RandomHelper.NetxtString(4, false);</para>        /// </summary>        /// <param name="size">字符串長度</param>        /// <param name="lowerCase">字符串是小寫</param>        /// <returns>隨機字符串</returns>        public static string NetxtString(int size, bool lowerCase)        {            Random _random = new Random((int)(DateTime.Now.Ticks));            StringBuilder _builder = new StringBuilder(size);            int _startChar = lowerCase ? 97 : 65;//65 = A / 97 = a            for (int i = 0; i < size; i++)                _builder.Append((char)(26 * _random.NextDouble() + _startChar));            return _builder.ToString();        }        #endregion        #region  0~9 A~Z字符串        /// <summary>        /// 0~9 A~Z字符串        /// </summary>        public static string RandomString_09AZ = "0123456789ABCDEFGHIJKMLNOPQRSTUVWXYZ";        #endregion        #region 依據指定字符串來生成隨機字符串        /// <summary>        /// 依據指定字符串來生成隨機字符串        /// <para>RandomHelper.NetxtString(RandomHelper.RandomString_09AZ, 4, false);</para>        /// </summary>        /// <param name="randomString">指定字符串</param>        /// <param name="size">字符串長度</param>        /// <param name="lowerCase">字符串是小寫</param>        /// <returns>隨機字符串</returns>        public static string NetxtString(string randomString, int size, bool lowerCase)        {            string _nextString = string.Empty;            Random _random = new Random((int)(DateTime.Now.Ticks));            if (!string.IsNullOrEmpty(randomString))            {                StringBuilder _builder = new StringBuilder(size);                int _maxCount = randomString.Length - 1;                for (int i = 0; i < size; i++)                {                    int _number = _random.Next(0, _maxCount);                    _builder.Append(randomString[_number]);                }                _nextString = _builder.ToString();            }            return lowerCase ? _nextString.ToLower() : _nextString.ToUpper();        }        #endregion        #region 生成隨機時間        /// <summary>        /// 生成隨機時間        /// <para>RandomHelper.NextDateTime();</para>        /// </summary>        /// <returns>隨機時間</returns>        public static DateTime NextDateTime()        {            Random _random = new Random((int)(DateTime.Now.Ticks));            int _hour = _random.Next(2, 5);            int _minute = _random.Next(0, 60);            int _second = _random.Next(0, 60);            string _dateTimeString = string.Format("{0} {1}:{2}:{3}", DateTime.Now.ToString("yyyy-MM-dd"), _hour, _minute, _second);            DateTime _nextTime = Convert.ToDateTime(_dateTimeString);            return _nextTime;        }        #endregion        #region  生成隨機MAC地址        /// <summary>        /// 生成隨機MAC地址        /// <para>RandomHelper.NextMacAddress();</para>        /// </summary>        /// <returns>新的MAC地址</returns>        public static string NextMacAddress()        {            int _minValue = 0, _maxValue = 16;            Random _random = new Random((int)(DateTime.Now.Ticks));            string _newMacAddress = string.Format("{0}{1}:{2}{3}:{4}{5}:{6}{7}:{8}{9}:{10}{11}",               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x"),               _random.Next(_minValue, _maxValue).ToString("x")                ).ToUpper();            return _newMacAddress;        }        #endregion    }}