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+package cc.iotkit.common.utils;
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+
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+
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+import java.net.InetAddress;
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+import java.net.NetworkInterface;
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+import java.net.SocketException;
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+import java.net.UnknownHostException;
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+import java.util.Enumeration;
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+import java.util.HashSet;
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+import java.util.Random;
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+import java.util.Set;
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+
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+/**
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+ * @author: Longjun.Tu
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+ * @description:
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+ * @date:created in 2023/5/18 10:20
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+ * @modificed by:
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+ */
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+public class SnowflakeIdGeneratorUtil {
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+
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+ /**
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+ * 起始的时间戳
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+ */
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+ private final static long START_STMP = 1577808000000L;
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+
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+ /**
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+ * 每一部分占用的位数
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+ */
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+ private final static long SEQUENCE_BIT = 12; //序列号占用的位数
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+ private final static long MACHINE_BIT = 5; //机器标识占用的位数
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+ private final static long DATACENTER_BIT = 5;//数据中心占用的位数
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+
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+ /**
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+ * 每一部分的最大值
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+ */
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+ private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
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+ private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
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+ private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);
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+
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+ /**
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+ * 每一部分向左的位移
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+ */
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+ private final static long MACHINE_LEFT = SEQUENCE_BIT;
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+ private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
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+ private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;
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+
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+ private long datacenterId; //数据中心
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+ private long machineId; //机器标识
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+ private long sequence = 0L; //序列号
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+ private long lastStmp = -1L;//上一次时间戳
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+
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+ private static volatile SnowflakeIdGeneratorUtil snowflake = null;
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+ private static Object lock = new Object();
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+
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+ public SnowflakeIdGeneratorUtil(long datacenterId, long machineId) {
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+ if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
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+ throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
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+ }
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+ if (machineId > MAX_MACHINE_NUM || machineId < 0) {
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+ throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
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+ }
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+ this.datacenterId = datacenterId;
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+ this.machineId = machineId;
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+ }
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+
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+ /**
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+ * 获取单列
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+ *
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+ * @return
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+ */
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+ public static SnowflakeIdGeneratorUtil getInstanceSnowflake() {
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+ if (snowflake == null) {
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+ synchronized (lock) {
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+ if(snowflake == null){
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+ long workerId;
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+ long dataCenterId = getRandom();
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+ try {
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+ //第一次使用获取mac地址的
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+ workerId = getWorkerId();
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+ } catch (Exception e) {
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+ workerId = getRandom();
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+ }
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+ snowflake = new SnowflakeIdGeneratorUtil(dataCenterId, workerId);
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+ }
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+ }
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+ }
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+ return snowflake;
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+ }
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+
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+ /**
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+ * 产生下一个ID
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+ *
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+ * @return
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+ */
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+ public synchronized long nextId() {
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+ long currStmp = getNewstmp();
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+ if (currStmp < lastStmp) {
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+ throw new RuntimeException("Clock moved backwards. Refusing to generate id");
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+ }
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+
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+ if (currStmp == lastStmp) {
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+ //相同毫秒内,序列号自增
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+ sequence = (sequence + 1) & MAX_SEQUENCE;
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+ //同一毫秒的序列数已经达到最大
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+ if (sequence == 0L) {
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+ currStmp = getNextMill();
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+ }
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+ } else {
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+ //不同毫秒内,序列号置为0
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+ sequence = 0L;
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+ }
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+
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+ lastStmp = currStmp;
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+
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+ return (currStmp - START_STMP) << TIMESTMP_LEFT //时间戳部分
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+ | datacenterId << DATACENTER_LEFT //数据中心部分
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+ | machineId << MACHINE_LEFT //机器标识部分
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+ | sequence; //序列号部分
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+ }
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+
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+ private long getNextMill() {
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+ long mill = getNewstmp();
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+ while (mill <= lastStmp) {
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+ mill = getNewstmp();
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+ }
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+ return mill;
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+ }
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+
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+ private long getNewstmp() {
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+ return System.currentTimeMillis();
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+ }
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+
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+ /**
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+ * 生成1-31之间的随机数
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+ *
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+ * @return
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+ */
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+ private static long getRandom() {
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+ int max = (int) (MAX_MACHINE_NUM);
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+ int min = 1;
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+ Random random = new Random();
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+ long result = random.nextInt(max - min) + min;
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+ return result;
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+ }
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+
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+ private static long getWorkerId() throws SocketException, UnknownHostException, NullPointerException {
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+ @SuppressWarnings("unused")
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+ InetAddress ip = InetAddress.getLocalHost();
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+
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+ NetworkInterface network = null;
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+ Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces();
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+ while (en.hasMoreElements()) {
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+ NetworkInterface nint = en.nextElement();
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+ if (!nint.isLoopback() && nint.getHardwareAddress() != null) {
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+ network = nint;
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+ break;
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+ }
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+ }
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+
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+ if (network == null) {
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+ throw new NullPointerException("network is null");
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+ }
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+ @SuppressWarnings("ConstantConditions")
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+ byte[] mac = network.getHardwareAddress();
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+ long id = ((0x000000FF & (long) mac[mac.length - 1]) | (0x0000FF00 & (((long) mac[mac.length - 2]) << 8))) >> 11;
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+ if (id > MAX_MACHINE_NUM) {
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+ return getRandom();
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+ }
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+ return id;
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+ }
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+
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+ public static void main(String[] args) {
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+ Set<Long> idList = new HashSet<>();
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+ long start = System.currentTimeMillis();
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+ for (int i = 0; i < 1000000; i++) {
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+ long id = SnowflakeIdGeneratorUtil.getInstanceSnowflake().nextId();
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+ idList.add(id);
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+ // System.out.println("id="+id);
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+ }
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+ // System.out.println(idList.size());
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+ // System.out.println(System.currentTimeMillis() - start);
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+ }
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+}
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