UUID & SnowflakeId 雪花算法package id; import java.util.UUID; /** * UUID * * @author ZengWenFeng * @date 2019.09.21 * @email 117791303@QQ.com * @mobile 13805029595 */ public class UuidUtil { // 带横线UUID public static String getUuid() { return UUID.randomUUID().toString(); } // 去除横线纯32位UUID public static String getSimpleUuid() { return UUID.randomUUID().toString().replace("-", ""); } public static void main(String[] args) { System.out.println(getUuid()); System.out.println(getSimpleUuid()); } }package id; /** * 雪花算法 ID 生成器 * 结构：0(符号位) + 41位时间戳 + 10位机器ID + 12位序列号 * * @author ZengWenFeng * @date 2019.09.21 * @email 117791303@QQ.com * @mobile 13805029595 */ public class SnowflakeIdGenerator { // 起始时间戳：2025-01-01 00:00:00 private static final long START_TIMESTAMP = 1735689600000L; // 机器ID位数 private static final long WORKER_ID_BITS = 10L; // 序列号位数 private static final long SEQUENCE_BITS = 12L; // 机器ID最大值 private static final long MAX_WORKER_ID = (1L << WORKER_ID_BITS) - 1; // 序列号最大值 private static final long MAX_SEQUENCE = (1L << SEQUENCE_BITS) - 1; // 机器ID左移位数 private static final long WORKER_ID_SHIFT = SEQUENCE_BITS; // 时间戳左移位数 private static final long TIMESTAMP_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS; // 机器ID private final long workerId; // 同一毫秒内序列号 private long sequence = 0L; // 上一次生成ID时间戳 private long lastTimestamp = -1L; public SnowflakeIdGenerator(long workerId) { if (workerId < 0 || workerId > MAX_WORKER_ID) { throw new IllegalArgumentException("机器ID范围 0~" + MAX_WORKER_ID); } this.workerId = workerId; } /** * 生成唯一ID */ public synchronized long nextId() { long currentTimestamp = getCurrentTime(); // 1. 时钟回拨处理 if (currentTimestamp < lastTimestamp) { throw new RuntimeException("系统时钟回拨，拒绝生成ID，差值：" + (lastTimestamp - currentTimestamp) + "ms"); } // 2. 同一毫秒内，自增序列号 if (currentTimestamp == lastTimestamp) { sequence = (sequence + 1) & MAX_SEQUENCE; // 序列号用尽，等待下一毫秒 if (sequence == 0) { currentTimestamp = waitNextMillis(lastTimestamp); } } else { // 新毫秒重置序列号 sequence = 0L; } lastTimestamp = currentTimestamp; // 拼接ID return ((currentTimestamp - START_TIMESTAMP) << TIMESTAMP_SHIFT) | (workerId << WORKER_ID_SHIFT) | sequence; } /** * 等待下一毫秒 */ private long waitNextMillis(long lastTs) { long ts = getCurrentTime(); while (ts <= lastTs) { ts = getCurrentTime(); } return ts; } private long getCurrentTime() { return System.currentTimeMillis(); } // 测试 public static void main(String[] args) { // 单机部署 workerId 填 0 即可，分布式不同机器配置不同ID SnowflakeIdGenerator generator = new SnowflakeIdGenerator(0); for (int i = 0; i < 10; i++) { System.out.println(generator.nextId()); } } }package id; import java.util.UUID; import java.util.concurrent.CountDownLatch; /** * 测试 * * @author ZengWenFeng * @date 2019.09.21 * @email 117791303@QQ.com * @mobile 13805029595 */ public class IdPerformanceTest { public static void main(String[] args) throws InterruptedException { int threadNum = 10; int countPerThread = 100000; final CountDownLatch latch = new CountDownLatch(threadNum); final SnowflakeIdGenerator snow = new SnowflakeIdGenerator(0); // 雪花算法压测 long startSnow = System.currentTimeMillis(); for (int t = 0; t < threadNum; t++) { new Thread(new Runnable() { public void run() { for (int i = 0; i < countPerThread; i++) { snow.nextId(); } latch.countDown(); } }).start(); } latch.await(); long snowCost = System.currentTimeMillis() - startSnow; System.out.println("SnowflakeId 10线程共" + threadNum * countPerThread + "个ID，耗时：" + snowCost + "ms"); // UUID压测 final CountDownLatch uuidLatch = new CountDownLatch(threadNum); long startUuid = System.currentTimeMillis(); for (int t = 0; t < threadNum; t++) { new Thread(new Runnable() { public void run() { for (int i = 0; i < countPerThread; i++) { UUID.randomUUID(); } uuidLatch.countDown(); } }).start(); } uuidLatch.await(); long uuidCost = System.currentTimeMillis() - startUuid; System.out.println("UUID 10线程共" + threadNum * countPerThread + "个ID，耗时：" + uuidCost + "ms"); } }
