我使用此代码将UUID转换为字节
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,如果我尝试使用此功能重新创建UUID,
public UUID frombyte(byte[] b)
{
return UUID.nameUUIDFromBytes(b);
}
这是不一样的UUID.转换一个randomUUID来回返回两个不同的.
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
解决方法
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);
}
