using System;

public class Program

{

    public static void Main()

    {

        /*IdWorker idworker = new IdWorker(1);

        for (int i = 0; i < 1000; i++)

        {

          Console.WriteLine(idworker.nextId());

        }*/

        Console.WriteLine(DateTime.Now.ToString("yyyyMMddHHmmssfff"));

    }

}

​

public class IdWorker

{

    private static long workerId;

    private static long twepoch = 687888001020L; //唯一时间，这是一个避免重复的随机量，自行设定不要大于当前时间戳

    private static long sequence = 0L;

    private static int workerIdBits = 4; //机器码字节数。4个字节用来保存机器码(定义为Long类型会出现，最大偏移64位，所以左移64位没有意义)

    public static long maxWorkerId = -1L ^ -1L << workerIdBits; //最大机器ID

    private static int sequenceBits = 10; //计数器字节数，10个字节用来保存计数码

    private static int workerIdShift = sequenceBits; //机器码数据左移位数，就是后面计数器占用的位数

    private static int timestampLeftShift = sequenceBits + workerIdBits; //时间戳左移动位数就是机器码和计数器总字节数

    public static long sequenceMask = -1L ^ -1L << sequenceBits; //一微秒内可以产生计数，如果达到该值则等到下一微妙在进行生成

    private long lastTimestamp = -1L;

​

    /// <summary>

    /// 机器码

    /// </summary>

    /// <param name="workerId"></param>

    public IdWorker(long workerId)

    {

        if (workerId > maxWorkerId || workerId < 0)

            throw new Exception(string.Format("worker Id can't be greater than {0} or less than 0 ", workerId));

        IdWorker.workerId = workerId;

    }

​

    public long nextId()

    {

        lock (this)

        {

            long timestamp = timeGen();

            if (this.lastTimestamp == timestamp)

            { //同一微妙中生成ID

                IdWorker.sequence = (IdWorker.sequence + 1) & IdWorker.sequenceMask; //用&运算计算该微秒内产生的计数是否已经到达上限

                if (IdWorker.sequence == 0)

                {

                    //一微妙内产生的ID计数已达上限，等待下一微妙

                    timestamp = tillNextMillis(this.lastTimestamp);

                }

            }

            else

            { //不同微秒生成ID

                IdWorker.sequence = 0; //计数清0

            }

            if (timestamp < lastTimestamp)

            { //如果当前时间戳比上一次生成ID时时间戳还小，抛出异常，因为不能保证现在生成的ID之前没有生成过

                throw new Exception(string.Format("Clock moved backwards.  Refusing to generate id for {0} milliseconds",

                    this.lastTimestamp - timestamp));

            }

            this.lastTimestamp = timestamp; //把当前时间戳保存为最后生成ID的时间戳

            long nextId = (timestamp - twepoch << timestampLeftShift) | IdWorker.workerId << IdWorker.workerIdShift | IdWorker.sequence;

            return nextId;

        }

    }

​

    /// <summary>

    /// 获取下一微秒时间戳

    /// </summary>

    /// <param name="lastTimestamp"></param>

    /// <returns></returns>

    private long tillNextMillis(long lastTimestamp)

    {

        long timestamp = timeGen();

        while (timestamp <= lastTimestamp)

        {

            timestamp = timeGen();

        }

        return timestamp;

    }

​

    /// <summary>

    /// 生成当前时间戳

    /// </summary>

    /// <returns></returns>

    private long timeGen()

    {

        return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;

    }

}