hienlt0610
10/30/2019 - 10:42 AM
[Java] ULID Generate Unique ID
/**
* MIT License
*
* Copyright (c) 2016 Azamshul Azizy
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package io.azam.ulidj;
import java.util.Random;
/**
* ULID string generator and parser class, using Crockford Base32 encoding. Only
* upper case letters are used for generation. Parsing allows upper and lower
* case letters, and i and l will be treated as 1 and o will be treated as 0.
* <br>
* <br>
* ULID generation examples:<br>
*
* <pre>
* String ulid1 = ULID.random();
* String ulid2 = ULID.random(ThreadLocalRandom.current());
* String ulid3 = ULID.random(SecureRandom.newInstance("SHA1PRNG"));
* byte[] entropy = new byte[] { 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9 };
* String ulid4 = ULID.generate(System.currentTimeMillis(), entropy);
* </pre>
*
* ULID parsing examples:<br>
*
* <pre>
* String ulid = "003JZ9J6G80123456789abcdef";
* assert ULID.isValid(ulid);
* long ts = ULID.getTimestamp(ulid);
* assert ts == 123456789000L;
* byte[] entropy = ULID.getEntropy(ulid);
* </pre>
*
* @author azam
* @since 0.0.1
*
* @see <a href="http://www.crockford.com/wrmg/base32.html">Base32 Encoding</a>
* @see <a href="https://github.com/alizain/ulid">ULID</a>
*/
public class ULID {
/**
* ULID string length.
*/
public static final int ULID_LENGTH = 26;
/**
* Minimum allowed timestamp value.
*/
public static final long MIN_TIME = 0x0L;
/**
* Maximum allowed timestamp value.
*/
public static final long MAX_TIME = 0x0000ffffffffffffL;
/**
* Base32 characters mapping
*/
private static final char[] C = new char[] { //
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, //
0x38, 0x39, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, //
0x47, 0x48, 0x4a, 0x4b, 0x4d, 0x4e, 0x50, 0x51, //
0x52, 0x53, 0x54, 0x56, 0x57, 0x58, 0x59, 0x5a };
/**
* {@code char} to {@code byte} O(1) mapping with alternative chars mapping
*/
private static final byte[] V = new byte[] { //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0x00, (byte) 0x01, (byte) 0x02, (byte) 0x03, //
(byte) 0x04, (byte) 0x05, (byte) 0x06, (byte) 0x07, //
(byte) 0x08, (byte) 0x09, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0x0a, (byte) 0x0b, (byte) 0x0c, //
(byte) 0x0d, (byte) 0x0e, (byte) 0x0f, (byte) 0x10, //
(byte) 0x11, (byte) 0xff, (byte) 0x12, (byte) 0x13, //
(byte) 0xff, (byte) 0x14, (byte) 0x15, (byte) 0xff, //
(byte) 0x16, (byte) 0x17, (byte) 0x18, (byte) 0x19, //
(byte) 0x1a, (byte) 0xff, (byte) 0x1b, (byte) 0x1c, //
(byte) 0x1d, (byte) 0x1e, (byte) 0x1f, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0x0a, (byte) 0x0b, (byte) 0x0c, //
(byte) 0x0d, (byte) 0x0e, (byte) 0x0f, (byte) 0x10, //
(byte) 0x11, (byte) 0xff, (byte) 0x12, (byte) 0x13, //
(byte) 0xff, (byte) 0x14, (byte) 0x15, (byte) 0xff, //
(byte) 0x16, (byte) 0x17, (byte) 0x18, (byte) 0x19, //
(byte) 0x1a, (byte) 0xff, (byte) 0x1b, (byte) 0x1c, //
(byte) 0x1d, (byte) 0x1e, (byte) 0x1f, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, //
(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff //
};
/**
* Generate random ULID string using {@link java.util.Random} instance.
*
* @return ULID string
*/
public static String random() {
byte[] entropy = new byte[10];
Random random = new Random();
random.nextBytes(entropy);
return generate(System.currentTimeMillis(), entropy);
}
/**
* Generate random ULID string using provided {@link java.util.Random}
* instance.
*
* @param random
* {@link java.util.Random} instance
* @return ULID string
*/
public static String random(Random random) {
byte[] entropy = new byte[10];
random.nextBytes(entropy);
return generate(System.currentTimeMillis(), entropy);
}
/**
* Generate ULID from Unix epoch timestamp in millisecond and entropy bytes.
* Throws {@link java.lang.IllegalArgumentException} if timestamp is less
* than {@value #MIN_TIME}, is more than {@value #MAX_TIME}, or entropy
* bytes is null or less than 10 bytes.
*
* @param time
* Unix epoch timestamp in millisecond
* @param entropy
* Entropy bytes
* @return ULID string
*/
public static String generate(long time, byte[] entropy) {
if (time < MIN_TIME || time > MAX_TIME || entropy == null || entropy.length < 10) {
throw new IllegalArgumentException("Time is too long, or entropy is less than 10 bytes or null");
}
char[] chars = new char[26];
// time
chars[0] = C[((byte) (time >>> 45)) & 0x1f];
chars[1] = C[((byte) (time >>> 40)) & 0x1f];
chars[2] = C[((byte) (time >>> 35)) & 0x1f];
chars[3] = C[((byte) (time >>> 30)) & 0x1f];
chars[4] = C[((byte) (time >>> 25)) & 0x1f];
chars[5] = C[((byte) (time >>> 20)) & 0x1f];
chars[6] = C[((byte) (time >>> 15)) & 0x1f];
chars[7] = C[((byte) (time >>> 10)) & 0x1f];
chars[8] = C[((byte) (time >>> 5)) & 0x1f];
chars[9] = C[((byte) (time)) & 0x1f];
// entropy
chars[10] = C[(byte) ((entropy[0] & 0xff) >>> 3)];
chars[11] = C[(byte) (((entropy[0] << 2) | ((entropy[1] & 0xff) >>> 6)) & 0x1f)];
chars[12] = C[(byte) (((entropy[1] & 0xff) >>> 1) & 0x1f)];
chars[13] = C[(byte) (((entropy[1] << 4) | ((entropy[2] & 0xff) >>> 4)) & 0x1f)];
chars[14] = C[(byte) (((entropy[2] << 5) | ((entropy[3] & 0xff) >>> 7)) & 0x1f)];
chars[15] = C[(byte) (((entropy[3] & 0xff) >>> 2) & 0x1f)];
chars[16] = C[(byte) (((entropy[3] << 3) | ((entropy[4] & 0xff) >>> 5)) & 0x1f)];
chars[17] = C[(byte) (entropy[4] & 0x1f)];
chars[18] = C[(byte) ((entropy[5] & 0xff) >>> 3)];
chars[19] = C[(byte) (((entropy[5] << 2) | ((entropy[6] & 0xff) >>> 6)) & 0x1f)];
chars[20] = C[(byte) (((entropy[6] & 0xff) >>> 1) & 0x1f)];
chars[21] = C[(byte) (((entropy[6] << 4) | ((entropy[7] & 0xff) >>> 4)) & 0x1f)];
chars[22] = C[(byte) (((entropy[7] << 5) | ((entropy[8] & 0xff) >>> 7)) & 0x1f)];
chars[23] = C[(byte) (((entropy[8] & 0xff) >>> 2) & 0x1f)];
chars[24] = C[(byte) (((entropy[8] << 3) | ((entropy[9] & 0xff) >>> 5)) & 0x1f)];
chars[25] = C[(byte) (entropy[9] & 0x1f)];
return new String(chars);
}
/**
* Checks ULID string validity.
*
* @param ulid
* ULID string
* @return true if ULID string is valid
*/
public static boolean isValid(CharSequence ulid) {
if (ulid == null || ulid.length() != ULID_LENGTH) {
return false;
}
for (int i = 0; i < ULID_LENGTH; i++) {
/** We only care for chars between 0x00 and 0xff. */
char c = ulid.charAt(i);
if (c < 0 || c > V.length || V[c] == (byte) 0xff) {
return false;
}
}
return true;
}
/**
* Extract and return the timestamp part from ULID. Expects a valid ULID
* string. Call {@link io.azam.ulidj.ULID#isValid(CharSequence)} and check
* validity before calling this method if you do not trust the origin of the
* ULID string.
*
* @param ulid
* ULID string
* @return Unix epoch timestamp in millisecond
*/
public static long getTimestamp(CharSequence ulid) {
return (long) V[ulid.charAt(0)] << 45 //
| (long) V[ulid.charAt(1)] << 40 //
| (long) V[ulid.charAt(2)] << 35 //
| (long) V[ulid.charAt(3)] << 30 //
| (long) V[ulid.charAt(4)] << 25 //
| (long) V[ulid.charAt(5)] << 20 //
| (long) V[ulid.charAt(6)] << 15 //
| (long) V[ulid.charAt(7)] << 10 //
| (long) V[ulid.charAt(8)] << 5 //
| (long) V[ulid.charAt(9)];
}
/**
* Extract and return the entropy part from ULID. Expects a valid ULID
* string. Call {@link io.azam.ulidj.ULID#isValid(CharSequence)} and check
* validity before calling this method if you do not trust the origin of the
* ULID string.
*
* @param ulid
* ULID string
* @return Entropy bytes
*/
public static byte[] getEntropy(CharSequence ulid) {
byte[] bytes = new byte[10];
bytes[0] = (byte) ((V[ulid.charAt(10)] << 3) //
| (V[ulid.charAt(11)] & 0xff) >>> 2);
bytes[1] = (byte) ((V[ulid.charAt(11)] << 6) //
| V[ulid.charAt(12)] << 1 //
| (V[ulid.charAt(13)] & 0xff) >>> 4);
bytes[2] = (byte) ((V[ulid.charAt(13)] << 4) //
| (V[ulid.charAt(14)] & 0xff) >>> 1);
bytes[3] = (byte) ((V[ulid.charAt(14)] << 7) //
| V[ulid.charAt(15)] << 2 //
| (V[ulid.charAt(16)] & 0xff) >>> 3);
bytes[4] = (byte) ((V[ulid.charAt(16)] << 5) //
| V[ulid.charAt(17)]);
bytes[5] = (byte) ((V[ulid.charAt(18)] << 3) //
| (V[ulid.charAt(19)] & 0xff) >>> 2);
bytes[6] = (byte) ((V[ulid.charAt(19)] << 6) //
| V[ulid.charAt(20)] << 1 //
| (V[ulid.charAt(21)] & 0xff) >>> 4);
bytes[7] = (byte) ((V[ulid.charAt(21)] << 4) //
| (V[ulid.charAt(22)] & 0xff) >>> 1);
bytes[8] = (byte) ((V[ulid.charAt(22)] << 7) //
| V[ulid.charAt(23)] << 2 //
| (V[ulid.charAt(24)] & 0xff) >>> 3);
bytes[9] = (byte) ((V[ulid.charAt(24)] << 5) //
| V[ulid.charAt(25)]);
return bytes;
}
}