package cn.studyjava.util;
/**
* @author zsljava@163.com
* JavaScript整数最大支持53位
* 时间41位 机器号1位 毫秒ID自增6位 一共48位
*/
public class IdWorker {
/**
* 2016-01-01 00:00:00
*/
private final static long twepoch = 1451577600000L;
/**
* 机器标识位数
*/
private final static long workerIdBits = 1L;
/**
* 机器ID支持机器节点数0~1
*/
public final static long maxWorkerId = ~(-1L << workerIdBits);
/**
* 毫秒内自增位
*/
private final static long sequenceBits = 6L;
/**
* 毫秒内sequence范围0~63
*/
public final static long sequenceMask = ~(-1L << sequenceBits);
/**
* 机器ID偏左移6位
*/
private final static long workerIdShift = sequenceBits;
/**
* 时间毫秒左移7位
*/
private final static long timestampLeftShift = sequenceBits + workerIdBits;
private final long workerId;
private long sequence = 0L;
private long lastTimestamp = -1L;
public IdWorker(final long workerId) {
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
this.workerId = workerId;
}
public synchronized long nextId() {
long timestamp = this.timeGen();
if (timestamp < this.lastTimestamp) {
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", this.lastTimestamp - timestamp));
}
if (this.lastTimestamp == timestamp) {
this.sequence = (this.sequence + 1) & sequenceMask;
if (this.sequence == 0) {
timestamp = this.tilNextMillis(this.lastTimestamp);
}
}
else {
this.sequence = 0;
}
this.lastTimestamp = timestamp;
return ((timestamp - twepoch << timestampLeftShift)) | (this.workerId << workerIdShift) | (this.sequence);
}
private long tilNextMillis(final long lastTimestamp) {
long timestamp = this.timeGen();
while (timestamp <= lastTimestamp) {
timestamp = this.timeGen();
}
return timestamp;
}
private long timeGen() {
return System.currentTimeMillis();
}
}
注意：本文归作者所有，未经作者允许，不得转载
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