雪花算法生成id的方法：首先新建一个id生成的类；然后新建一个调用生成id的单例工具；最后使用函数【GuuidUtil.getUUID()】直接调用即可。

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雪花算法生成id的方法：

1、新建一个id生成的类 SnowFlake/**

* @Auther: lyl

* @Date: 2019/11/21 17:49

* @Description:

*/

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 TIMESTMP_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) << 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

}

private long getNextMill() {

long mill = getNewstmp();

while (mill <= lastStmp) {

mill = getNewstmp();

}

return mill;

}

private long getNewstmp() {

return System.currentTimeMillis();

}

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());

}

}

}

2、为防止多线程生成重复的id，这边新建了一个调用生成id的单例工具

其中machineId和datacenterId可以放在配置文件中import java.util.concurrent.CountDownLatch;

/**

* @Auther: lyl

* @Date: 2019/11/21 18:15

* @Description:

*/

public class GuuidUtil {

private static long machineId = 0;

private static long datacenterId = 0;

/**

* 单例模式创建学法算法对象

* */

private enum SnowFlakeSingleton{

Singleton;

private SnowFlake snowFlake;

SnowFlakeSingleton(){

snowFlake = new SnowFlake(datacenterId,machineId);

}

public SnowFlake getInstance(){

return snowFlake;

}

}

public static long getUUID(){

return SnowFlakeSingleton.Singleton.getInstance().nextId();

}

public static void main(String[] args) {

CountDownLatch latch = new CountDownLatch(10000);

long start = System.currentTimeMillis();

for (int i = 0; i < 10000; i++) {

new Runnable() {

@Override

public void run() {

System.out.println(GuuidUtil.getUUID());

latch.countDown();

}

}.run();

}

try {

System.out.println("主线程"+Thread.currentThread().getName()+"等待子线程执行完成...");

latch.await();//阻塞当前线程，直到计数器的值为0

System.out.println("主线程"+Thread.currentThread().getName()+"开始执行...");

} catch (InterruptedException e) {

e.printStackTrace();

}

System.out.print("雪花算法用时： ");

System.out.println(System.currentTimeMillis() - start);

}

}

最后直接调用：GuuidUtil.getUUID()；就可以直接生成id想了解更多编程学习，敬请关注php培训栏目！