java中snowflake_snowflake java实现

snowflake java版

package com.example.demo;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class IdWorker {

protected static final Logger LOG = LoggerFactory.getLogger(IdWorker.class);

private long workerId;

private long datacenterId;

private long sequence = 0L;

private long twepoch = 1288834974657L;

private long workerIdBits = 5L;

private long datacenterIdBits = 5L;

private long maxWorkerId = -1L ^ (-1L << workerIdBits);

private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);

private long sequenceBits = 12L;

private long workerIdShift = sequenceBits;

private long datacenterIdShift = sequenceBits + workerIdBits;

private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;

private long sequenceMask = -1L ^ (-1L << sequenceBits);

private long lastTimestamp = -1L;

public IdWorker(long workerId, long datacenterId) {

// sanity check for workerId

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;

LOG.info(String.format("worker starting. timestamp left shift %d, datacenter id bits %d, worker id bits %d, sequence bits %d, workerid %d", timestampLeftShift, datacenterIdBits, workerIdBits, sequenceBits, workerId));

}

public synchronized long nextId() {

long timestamp = timeGen();

if (timestamp < lastTimestamp) {

LOG.error(String.format("clock is moving backwards. Rejecting requests until %d.", 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();

}

}

IdWorker.java

package com.example.demo;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

* Created by Pumelo.

* Mail: 535553297@qq.com

* Date: 2017/11/11

*/

public class IdWorker {

protected static final Logger LOG = LoggerFactory.getLogger(IdWorker.class);

private long workerId;

private long datacenterId;

private long sequence = 0L;

private long twepoch = 1288834974657L;

private long workerIdBits = 5L;

private long datacenterIdBits = 5L;

private long maxWorkerId = -1L ^ (-1L << workerIdBits);

private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);

private long sequenceBits = 12L;

private long workerIdShift = sequenceBits;

private long datacenterIdShift = sequenceBits + workerIdBits;

private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;

private long sequenceMask = -1L ^ (-1L << sequenceBits);

private long lastTimestamp = -1L;

public IdWorker(long workerId, long datacenterId) {

// sanity check for workerId

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;

LOG.info(String.format("worker starting. timestamp left shift %d, datacenter id bits %d, worker id bits %d, sequence bits %d, workerid %d", timestampLeftShift, datacenterIdBits, workerIdBits, sequenceBits, workerId));

}

public synchronized long nextId() {

long timestamp = timeGen();

if (timestamp < lastTimestamp) {

LOG.error(String.format("clock is moving backwards. Rejecting requests until %d.", 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();

}

}