随机数的生成方法

整理随机数、随机字符串的生成方法：

        #region 生成随机数字
        /// <summary>
        /// 生成随机数字
        /// </summary>
        /// <param name="length">生成长度</param>
        /// <returns></returns>
        public static string Number(int length)
        {
            return Number(length, false);
        }
        #endregion

        #region 生成随机数字(有线程睡眠时间)
        /// <summary>
        /// 生成随机数字(有线程睡眠时间)
        /// </summary>
        /// <param name="length">生成随机数的长度</param>
        /// <param name="sleep">是否要在生成前将当前线程阻止以避免重复</param>
        /// <param name="millisecondsTimeout">线程睡眠时间</param>
        /// <returns></returns>
        public static string Number(int length, bool sleep, int millisecondsTimeout = 3)
        {
            if (sleep)
            {
                System.Threading.Thread.Sleep(millisecondsTimeout);
            }
            string result = "";
            System.Random random = new Random();
            for (int i = 0; i < length; i++)
            {
                result += random.Next(10).ToString();
            }
            return result;
        }
        #endregion

        #region 生成随机字母字符串(数字字母混和)
        /// <summary>
        /// 生成随机字母字符串(数字字母混和)
        /// </summary>
        /// <param name="length">待生成的随机数位数</param>
        /// <returns></returns>
        public static string GetNumberCode(int length)
        {
            string str = string.Empty;
            int rep = 0;
            long num2 = DateTime.Now.Ticks + rep;
            rep++;
            Random random = new Random(((int)(((ulong)num2) & 0xffffffffL)) | ((int)(num2 >> rep)));
            for (int i = 0; i < length; i++)
            {
                char ch;
                int num = random.Next();
                if ((num % 2) == 0)
                {
                    ch = (char)(0x30 + ((ushort)(num % 10)));
                }
                else
                {
                    ch = (char)(0x41 + ((ushort)(num % 0x1a)));
                }
                str = str + ch.ToString();
            }
            return str;
        }
        #endregion