C02TobNClov1Dz56
49 天前
//这里有个简单的实现, 我也不知道摘抄自哪里了
import java.nio.ByteBuffer;
import java.security.SecureRandom;
import java.util.UUID;
/**
* 时间顺序的 UUID
*/
public class UUIDv7 {
private static final SecureRandom random = new SecureRandom();
public static UUID randomUUID() {
byte[] value = randomBytes();
ByteBuffer buf = ByteBuffer.wrap(value);
long high = buf.getLong();
long low = buf.getLong();
return new UUID(high, low);
}
private static byte[] randomBytes() {
// random bytes
byte[] value = new byte[16];
random.nextBytes(value);
// current timestamp in ms
ByteBuffer timestamp = ByteBuffer.allocate(Long.BYTES);
timestamp.putLong(System.currentTimeMillis());
// timestamp
System.arraycopy(timestamp.array(), 2, value, 0, 6);
// version and variant
value[6] = (byte) ((value[6] & 0x0F) | 0x70);
value[8] = (byte) ((value[8] & 0x3F) | 0x80);
return value;
}
// public static void main(String[] args) {
// UUID uuid = UUIDv7.randomUUID();
// System.out.println(uuid);
// }
}