90 lines
2.9 KiB
Java
90 lines
2.9 KiB
Java
|
package io.dataease.utils;
|
|||
|
|
|
|||
|
|
public class SnowFlake {
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* 起始的时间戳
|
|||
|
|
*/
|
|||
|
|
private final static long START_STMP = 1480166465631L;
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* 每一部分占用的位数
|
|||
|
|
*/
|
|||
|
|
private final static long SEQUENCE_BIT = 12; //序列号占用的位数
|
|||
|
|
private final static long MACHINE_BIT = 5; //机器标识占用的位数
|
|||
|
|
private final static long DATACENTER_BIT = 5;//数据中心占用的位数
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* 每一部分的最大值
|
|||
|
|
*/
|
|||
|
|
private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
|
|||
|
|
private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
|
|||
|
|
private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* 每一部分向左的位移
|
|||
|
|
*/
|
|||
|
|
private final static long MACHINE_LEFT = SEQUENCE_BIT;
|
|||
|
|
private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
|
|||
|
|
private final static long TIMESTAMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
|
|||
|
|
|
|||
|
|
private long datacenterId; //数据中心
|
|||
|
|
private long machineId; //机器标识
|
|||
|
|
private long sequence = 0L; //序列号
|
|||
|
|
private long lastStmp = -1L;//上一次时间戳
|
|||
|
|
|
|||
|
|
public SnowFlake(long datacenterId, long machineId) {
|
|||
|
|
if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
|
|||
|
|
throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
|
|||
|
|
}
|
|||
|
|
if (machineId > MAX_MACHINE_NUM || machineId < 0) {
|
|||
|
|
throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
|
|||
|
|
}
|
|||
|
|
this.datacenterId = datacenterId;
|
|||
|
|
this.machineId = machineId;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* 产生下一个ID
|
|||
|
|
*
|
|||
|
|
* @return
|
|||
|
|
*/
|
|||
|
|
public synchronized long nextId() {
|
|||
|
|
long currStmp = getNewstmp();
|
|||
|
|
if (currStmp < lastStmp) {
|
|||
|
|
throw new RuntimeException("Clock moved backwards. Refusing to generate id");
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if (currStmp == lastStmp) {
|
|||
|
|
//相同毫秒内，序列号自增
|
|||
|
|
sequence = (sequence + 1) & MAX_SEQUENCE;
|
|||
|
|
//同一毫秒的序列数已经达到最大
|
|||
|
|
if (sequence == 0L) {
|
|||
|
|
currStmp = getNextMill();
|
|||
|
|
}
|
|||
|
|
} else {
|
|||
|
|
//不同毫秒内，序列号置为0
|
|||
|
|
sequence = 0L;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
lastStmp = currStmp;
|
|||
|
|
|
|||
|
|
return (currStmp - START_STMP) << TIMESTAMP_LEFT //时间戳部分
|
|||
|
|
| datacenterId << DATACENTER_LEFT //数据中心部分
|
|||
|
|
| machineId << MACHINE_LEFT //机器标识部分
|
|||
|
|
| sequence; //序列号部分
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private long getNextMill() {
|
|||
|
|
long mill = getNewstmp();
|
|||
|
|
while (mill <= lastStmp) {
|
|||
|
|
mill = getNewstmp();
|
|||
|
|
}
|
|||
|
|
return mill;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private long getNewstmp() {
|
|||
|
|
return System.currentTimeMillis();
|
|||
|
|
}
|
|||
|
|
}
|