IdWorker-UUID生成器

public class IdWorker {
private final long twepoch = 1288834974657L;
private final long workerIdBits = 5L;
private final long datacenterIdBits = 5L;
private final long maxWorkerId = -1L ^ (-1L << workerIdBits);
private final long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
private final long sequenceBits = 12L;
private final long workerIdShift = sequenceBits;
private final long datacenterIdShift = sequenceBits + workerIdBits;
private final long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
private final long sequenceMask = -1L ^ (-1L << sequenceBits);

private long workerId;private long datacenterId;private long sequence = 0L;private long lastTimestamp = -1L;public IdWorker(long workerId, long datacenterId) {    if (workerId > maxWorkerId || workerId < 0) {        throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));    }    if (datacenterId > maxDatacenterId || datacenterId < 0) {        throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));    }    this.workerId = workerId;    this.datacenterId = datacenterId;}public synchronized long nextId() {    long timestamp = timeGen();    if (timestamp < lastTimestamp) {        throw new RuntimeException(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));    }    if (lastTimestamp == timestamp) {        sequence = (sequence + 1) & sequenceMask;        if (sequence == 0) {            timestamp = tilNextMillis(lastTimestamp);        }           } else {        sequence = 0L;    }    lastTimestamp = timestamp;    return ((timestamp - twepoch) << timestampLeftShift) | (datacenterId << datacenterIdShift) | (workerId << workerIdShift) | sequence;}protected long tilNextMillis(long lastTimestamp) {    long timestamp = timeGen();    while (timestamp <= lastTimestamp) {        timestamp = timeGen();    }    return timestamp;}protected long timeGen() {    return System.currentTimeMillis();}public static void main(String[] args) {    IdWorker idWorker = new IdWorker(0, 0);    for (int i = 0; i < 1000; i++) {        long id = idWorker.nextId();        System.out.println(id);    }}

}

/**
* @author Bean
* 参考twitter snowfake 的实现方式
* @see http://github.com/twitter/snowflake
*/
public class SnowflakeUUIDGenerator {

/** *  */public SnowflakeUUIDGenerator() {}

}