cn.acyou.leo.framework.commons.SnowFlake Maven / Gradle / Ivy
package cn.acyou.leo.framework.commons;
import java.net.InetAddress;
import java.net.UnknownHostException;
/**
* @author youfang
* @version [1.0.0, 2021-8-7]
**/
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 << DATACENTER_BIT);
private final static long MAX_MACHINE_NUM = ~(-1L << MACHINE_BIT);
private final static long MAX_SEQUENCE = ~(-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 TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
private final long datacenterId; //数据中心
private final long machineId; //机器标识
private long sequence = 0L; //序列号
private long lastStmp = -1L;//上一次时间戳
/**
* 雪花
*
* @param datacenterId 数据中心id 0~31
* @param machineId 机器标识id 0~31
*/
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;
}
public SnowFlake(){
this.datacenterId = 1;
this.machineId = 0x000000FF & getLastIp();
}
/**
* 产生下一个ID
*
* @return 产生Long类型ID
*/
public synchronized long nextId() {
long currStmp = getNewTimeMillis();
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) << TIMESTMP_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
}
/**
* 带前缀编号
*
* @param prefix 前缀
* @return NO32144324
*/
public synchronized String nextIdPrefix(String prefix) {
String id = String.valueOf(nextId());
if (prefix != null) {
return prefix + id;
}
return id;
}
/**
* 下一个ID（字符串形式）
*
* @return ID 字符串形式
*/
public synchronized String nextIdStr() {
return Long.toString(nextId());
}
private long getNextMill() {
long mill = getNewTimeMillis();
while (mill <= lastStmp) {
mill = getNewTimeMillis();
}
return mill;
}
private long getNewTimeMillis() {
return System.currentTimeMillis();
}
private byte getLastIp() {
byte lastip = 0;
try {
InetAddress ip = InetAddress.getLocalHost();
byte[] ipByte = ip.getAddress();
lastip = ipByte[ipByte.length - 1];
} catch (UnknownHostException e) {
//ignore
}
return lastip;
}
public static void main(String[] args) {
SnowFlake snowFlake = new SnowFlake(2, 3);
for (int i = 0; i < (1 << 12); i++) {
System.out.println(snowFlake.nextId());
}
System.out.println("=======================");
SnowFlake snowFlake2 = new SnowFlake();
for (int i = 0; i < (1 << 12); i++) {
System.out.println(snowFlake2.nextId());
}
}
}