原来 uuid v7 实现如此简单： - sp42_frank - 沸点 - 掘金

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原来 uuid v7 实现如此简单：

```java

import java.nio.ByteBuffer;
import java.security.SecureRandom;
import java.util.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;
}
}
```

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