C#和JAVA生成雪花ID代码

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c#：`public class IdWorker

{
    //机器ID
    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;
    }
}

`

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java：`public class IdWorker {

private final long workerId;
private final static long twepoch = 1288834974657L;
private long sequence = 0L;
private final static long workerIdBits = 4L;
public final static long maxWorkerId = -1L ^ -1L << workerIdBits;
private final static long sequenceBits = 10L;
private final static long workerIdShift = sequenceBits;
private final static long timestampLeftShift = sequenceBits + workerIdBits;
public final static long sequenceMask = -1L ^ -1L << sequenceBits;
private long lastTimestamp = -1L;
public IdWorker(final long workerId) {
    super();
    if (workerId > this.maxWorkerId || workerId < 0) {
          throw new IllegalArgumentException(String.format(
                                      "worker Id can't be greater than %d or less than 0",
                this.maxWorkerId));
    }
    this.workerId = workerId;
}
public synchronized long nextId() {
    long timestamp = this.timeGen();
    if (this.lastTimestamp == timestamp) {
        this.sequence = (this.sequence + 1) & this.sequenceMask;
        if (this.sequence == 0) {
            System.out.println("###########" + sequenceMask);
            timestamp = this.tilNextMillis(this.lastTimestamp);
         }
        } else {
            this.sequence = 0;
        }
        if (timestamp < this.lastTimestamp) {
            try {
                throw new Exception(
                      String.format(
                          "Clock moved backwards. Refusing to generate id for %d milliseconds",
                          this.lastTimestamp - timestamp));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    this.lastTimestamp = timestamp;
    long nextId = ((timestamp - twepoch << timestampLeftShift))
          | (this.workerId << this.workerIdShift) | (this.sequence);
    System.out.println("timestamp:" + timestamp + ",timestampLeftShift:"
                                  + timestampLeftShift + ",nextId:" + nextId + ",workerId:"
                                  + workerId + ",sequence:" + sequence);
    return nextId;
}

private long tilNextMillis(final long lastTimestamp) {
    long timestamp = this.timeGen();
    while (timestamp <= lastTimestamp) {
        timestamp = this.timeGen();
    }
    return timestamp;
}

private long timeGen() {
    return System.currentTimeMillis();
}

//调用
public static void main(String[] args){
    IdWorker worker2 = new IdWorker(2);
    System.out.println(worker2.nextId());
}

}
`

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