产生有序的全局唯一Id

Posted 2020-08-27 jeffrey77

//利用时间和Guid作为种子产生随机数
private string GenerateUniqueID()
{
      System.Text.StringBuilder sb = new System.Text.StringBuilder();
      string str1 = DateTime.Now.ToString("yyyyMMddHHmmss");
      Random d = new Random(Guid.NewGuid().GetHashCode());
      string str2 = d.Next(10000, 100000).ToString();
      return sb.Append(str1).Append(str2).ToString();
 }
　　

       //利用时间和RNGCryptoServiceProvider产生
        public static string GenerateOrderNumber()
        {
            string strDateTimeNumber = DateTime.Now.ToString("yyyyMMddHHmmssms");
            string strRandomResult = NextRandom(1000, 1).ToString();
            return strDateTimeNumber + strRandomResult;
        }

        /// <summary>
        /// 参考：msdn上的RNGCryptoServiceProvider例子
        /// </summary>
        /// <param name="numSeeds"></param>
        /// <param name="length"></param>
        /// <returns></returns>
        private static int NextRandom(int numSeeds, int length)
        {
            // Create a byte array to hold the random value.  
            byte[] randomNumber = new byte[length];
            // Create a new instance of the RNGCryptoServiceProvider.  
            System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
            // Fill the array with a random value.  
            rng.GetBytes(randomNumber);
            // Convert the byte to an uint value to make the modulus operation easier.  
            uint randomResult = 0x0;
            for (int i = 0; i < length; i++)
            {
                randomResult |= ((uint)randomNumber[i] << ((length - 1 - i) * 8));
            }
            return (int)(randomResult % numSeeds) + 1;
        }