将uuid转换为byte,在使用UUID.nameUUIDFromBytes(b)时有效 [英] convert uuid to byte, that works when using UUID.nameUUIDFromBytes(b)
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问题描述
我正在使用此代码将UUID转换为字节
I am converting UUID to byte using this code
public byte[] getIdAsByte(UUID uuid)
{
ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
bb.putLong(uuid.getMostSignificantBits());
bb.putLong(uuid.getLeastSignificantBits());
return bb.array();
}
但是,如果我尝试使用此函数重新创建UUID,
However, if I try to recreate the UUID using this function,
public UUID frombyte(byte[] b)
{
return UUID.nameUUIDFromBytes(b);
}
它与UUID不同。来回转换randomUUID会返回两个不同的。
It is not the same UUID. Converting a randomUUID back and forth returns two different it.
UUID u = UUID.randomUUID();
System.out.println(u.toString());
System.out.println(frombyte(getIdAsByte(u)).toString());
打印:
1ae004cf-0f48-469f-8a94-01339afaec41
8b5d1a71-a4a0-3b46-bec3-13ab9ab12e8e
推荐答案
public class UuidUtils {
public static UUID asUuid(byte[] bytes) {
ByteBuffer bb = ByteBuffer.wrap(bytes);
long firstLong = bb.getLong();
long secondLong = bb.getLong();
return new UUID(firstLong, secondLong);
}
public static byte[] asBytes(UUID uuid) {
ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
bb.putLong(uuid.getMostSignificantBits());
bb.putLong(uuid.getLeastSignificantBits());
return bb.array();
}
}
@Test
public void verifyUUIDBytesCanBeReconstructedBackToOriginalUUID() {
UUID u = UUID.randomUUID();
byte[] uBytes = UuidUtils.asBytes(u);
UUID u2 = UuidUtils.asUuid(uBytes);
Assert.assertEquals(u, u2);
}
@Test
public void verifyNameUUIDFromBytesMethodDoesNotRecreateOriginalUUID() {
UUID u = UUID.randomUUID();
byte[] uBytes = UuidUtils.asBytes(u);
UUID u2 = UUID.nameUUIDFromBytes(uBytes);
Assert.assertNotEquals(u, u2);
}
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