IdWorker.java

public class IdWorker {

	long workerBits = 5L;
	long datacenterBits = 5L;
	long sequenceBits = 12L;

	long workerIdShift = sequenceBits;
	long datacenterIdShift = sequenceBits + workerBits;
	long timestampLeftShift = sequenceBits + workerBits + datacenterBits;
	
	long sequenceMask = -1L ^ (-1L << sequenceBits);
	
	final long baseepoc = 1288834974657L;
	
	long sequence = 0;
	
	long lastTimestamp = -1L;
		
	public long nextId() {
		long timestamp = System.currentTimeMillis();
		
		long timeId = timestamp - baseepoc;
		long datacenterId = 1;
		long workerId = 3;

		if(timestamp == lastTimestamp) {
			sequence = (sequence + 1) & sequenceMask;
		}
		else {
			sequence = 0;
		}
		
		lastTimestamp = timestamp;
		
		long id = ((timeId) << timestampLeftShift) |
				(datacenterId << datacenterIdShift) |
				(workerId << workerIdShift) + sequence;
				
		return id;
	}
	
	public static void main(String...args) {
		IdWorker w = new IdWorker();
		long id = w.nextId();
		System.out.println(id);
		System.out.println(Long.toBinaryString(id));
		System.out.println(Long.toHexString(id));
	}
	
}