Created
November 8, 2020 20:41
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Base64 UUID with space for some flags
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| package dev.richst.libs.richuuid; | |
| import java.io.*; | |
| import java.util.Base64; | |
| import java.util.UUID; | |
| public class RichUuid { | |
| static byte[] uuidToByteArray(UUID uuid) { | |
| try { | |
| ByteArrayOutputStream bos = new ByteArrayOutputStream(); | |
| DataOutputStream dos = new DataOutputStream(bos); | |
| dos.writeLong(uuid.getMostSignificantBits()); | |
| dos.writeLong(uuid.getLeastSignificantBits()); | |
| dos.write(2); | |
| dos.flush(); | |
| return bos.toByteArray(); | |
| } catch (IOException ex) { | |
| // this should never be thrown, and there is no sensible way to handle it | |
| throw new IllegalStateException( | |
| "IO exception occurred working on memory backed streams", ex); | |
| } | |
| } | |
| static UUID byteArrayToUuid(byte[] uuidBytes) { | |
| try { | |
| ByteArrayInputStream bis = new ByteArrayInputStream(uuidBytes); | |
| DataInputStream dis = new DataInputStream(bis); | |
| long msb = dis.readLong(); | |
| long lsb = dis.readLong(); | |
| return new UUID(msb, lsb); | |
| } catch (IOException ex) { | |
| // this should never be thrown, and there is no sensible way to handle it | |
| throw new IllegalStateException( | |
| "IO exception occurred working on memory backed streams", ex); | |
| } | |
| } | |
| public static String fromUUID(UUID uuid) { | |
| byte[] uuidBytes = uuidToByteArray(uuid); | |
| byte[] uuidBytesWithChecksum = new byte[18]; | |
| int checksum = 0; | |
| for (int ii = 0; ii < 16; ii++) { | |
| uuidBytesWithChecksum[ii] = uuidBytes[ii]; | |
| checksum += uuidBytes[ii] & 0xFF; | |
| } | |
| uuidBytesWithChecksum[16] = 0; | |
| uuidBytesWithChecksum[17] = (byte) (checksum % 256); | |
| return Base64.getUrlEncoder().encodeToString(uuidBytesWithChecksum); | |
| } | |
| public static String generate() { | |
| return fromUUID(UUID.randomUUID()); | |
| } | |
| private static boolean validateChecksum(byte[] uuidBytesWithChecksum) { | |
| int checksum = 0; | |
| for (int ii = 0; ii < 17; ii++) { | |
| checksum += uuidBytesWithChecksum[ii] & 0xFF; | |
| } | |
| return ((byte) checksum) == uuidBytesWithChecksum[17]; | |
| } | |
| private static void assertChecksumValid(byte[] uuidBytes) { | |
| if (!validateChecksum(uuidBytes)) { | |
| throw new InvalidRichUuidException("checksum invalid"); | |
| } | |
| } | |
| public static UUID toUUID(String richUuid) { | |
| byte[] uuidBytesWithChecksum; | |
| try { | |
| uuidBytesWithChecksum = Base64.getUrlDecoder().decode(richUuid); | |
| } catch (IllegalArgumentException ex) { | |
| throw new InvalidRichUuidException("Could not base64 decode richUuid", ex); | |
| } | |
| if (uuidBytesWithChecksum.length != 18) { | |
| throw new InvalidRichUuidException("UUID length invalid"); | |
| } | |
| assertChecksumValid(uuidBytesWithChecksum); | |
| return byteArrayToUuid(uuidBytesWithChecksum); | |
| } | |
| } |
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