C#-Guid帮助类，用于生产连续的Guid

/************************************************************
* Description: Guid帮助类，用于生产连续的Guid
* Create Time: 2019-02-25
* Author：zh.z
* Version: v1.0.1
************************************************************/

using System;
using System.Security.Cryptography;

namespace BOZHON.TSAMO.Common
{
    public class GuidHelper
    {
        /// <summary>
        /// 获取GUID字符串（36位）
        /// </summary>
        /// <param name="upper">是否大写(默认fasle)</param>
        /// <param name="sequentialGuidType">类型</param>
        /// <returns></returns>
        public static string Get36(bool upper = false, SequentialGuidType sequentialGuidType = SequentialGuidType.SequentialAsBinary)
        {
            Guid guid = SequentialGuidGenerator.NewSequentialGuid(sequentialGuidType);
            string tmp = guid.ToString();
            return upper ? tmp.ToUpper() : tmp.ToLower();
        }

        /// <summary>
        /// 获取GUID字符串 （获取32位不包含“-”号的GUID字符串）
        /// </summary>
        /// <param name="upper">是否大写</param>
        /// <param name="sequentialGuidType">类型</param>
        /// <returns></returns>
        public static string Get32(bool upper = true, SequentialGuidType sequentialGuidType = SequentialGuidType.SequentialAsBinary)
        {
            Guid guid = SequentialGuidGenerator.NewSequentialGuid(sequentialGuidType);
            string tmp = guid.ToString("N");
            return upper ? tmp.ToUpper() : tmp.ToLower();
        }

        /// <summary>
        /// 获取GUID字符串  (获取32位包含“-”号的GUID字符串)
        /// </summary>
        /// <param name="upper">是否大写</param>
        /// <param name="sequentialGuidType">类型</param>
        /// <returns></returns>
        public static string Get32_(bool upper = true, SequentialGuidType sequentialGuidType = SequentialGuidType.SequentialAsBinary)
        {
            Guid guid = SequentialGuidGenerator.NewSequentialGuid(sequentialGuidType);
            string tmp = guid.ToString("D");
            return upper ? tmp.ToUpper() : tmp.ToLower();
        }

        /// <summary>
        /// 获取有序的唯一ID。
        /// </summary>
        /// <returns></returns>
        public static Guid GenerateComb(SequentialGuidType sequentialGuidType = SequentialGuidType.SequentialAsBinary)
        {
            return SequentialGuidGenerator.NewSequentialGuid(sequentialGuidType);
        }
        /// <summary>
        /// 根据枚举生成不同的有序GUID
        /// http://www.codeproject.com/Articles/388157/GUIDs-as-fast-primary-keys-under-multiple-database
        /// </summary>
        private static class SequentialGuidGenerator
        {
            private static readonly RNGCryptoServiceProvider Rng = new RNGCryptoServiceProvider();

            public static Guid NewSequentialGuid(SequentialGuidType guidType)
            {
                var randomBytes = new byte[10];
                Rng.GetBytes(randomBytes);

                var timestamp = DateTime.UtcNow.Ticks / 10000L;
                var timestampBytes = BitConverter.GetBytes(timestamp);

                if (BitConverter.IsLittleEndian)
                {
                    Array.Reverse(timestampBytes);
                }

                var guidBytes = new byte[16];

                switch (guidType)
                {
                    case SequentialGuidType.SequentialAsString:
                    case SequentialGuidType.SequentialAsBinary:
                        Buffer.BlockCopy(timestampBytes, 2, guidBytes, 0, 6);
                        Buffer.BlockCopy(randomBytes, 0, guidBytes, 6, 10);

                        // If formatting as a string, we have to reverse the order
                        // of the Data1 and Data2 blocks on little-endian systems.
                        if (guidType == SequentialGuidType.SequentialAsString && BitConverter.IsLittleEndian)
                        {
                            Array.Reverse(guidBytes, 0, 4);
                            Array.Reverse(guidBytes, 4, 2);
                        }
                        break;
                    case SequentialGuidType.SequentialAtEnd:
                        Buffer.BlockCopy(randomBytes, 0, guidBytes, 0, 10);
                        Buffer.BlockCopy(timestampBytes, 2, guidBytes, 10, 6);
                        break;
                    default:
                        throw new ArgumentOutOfRangeException("guidType", guidType, null);
                }

                return new Guid(guidBytes);
            }
        }
    }
    /// <summary>
    /// 有序GUID的类型
    /// <para>1. MSSQL 	        uniqueidentifier 	SequentialAtEnd </para>
    /// <para>2. MySQL 	        char(36) 	        SequentialAsString </para>
    /// <para>3. Oracle 	    raw(16) 	        SequentialAsBinary </para>
    /// <para>4. PostgreSQL     uuid 	            SequentialAsString </para>
    /// </summary>
    public enum SequentialGuidType
    {
        /// <summary>
        /// MySQL,PostgreSQL
        /// </summary>
        SequentialAsString,
        /// <summary>
        /// Oracle
        /// </summary>
        SequentialAsBinary,
        /// <summary>
        /// MSSQL
        /// </summary>
        SequentialAtEnd
    }
}