Java Digest digestBased(String text)

Description

Method used when an UUID must be generated using a string representation.

License

Open Source License

Parameter

Parameter	Description
text	The string using for the UUDI generation

Exception

Parameter	Description
NoSuchAlgorithmException	thrown if the MD5 digest algorithm is no available

Return

a valid UUID

Declaration

public static UUID digestBased(String text) throws NoSuchAlgorithmException 

Method Source Code

//package com.java2s;
/*// w w  w .  j  a v a  2  s.  c o m
 * Copyright (C)2012 D. Plaindoux.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.UUID;

public class Main {
    private static final int BYTE_SIZE = 8;
    private static final int BYTE_MASK = 0xFF;
    private static final int DIGEST_LEN = 16;

    /**
     * Method used when an UUID must be generated using a string representation.
     * This is done using the MD5 digest generated with the string argument.
     * 
     * @param text
     *            The string using for the UUDI generation
     * @return a valid UUID
     * @throws NoSuchAlgorithmException
     *             thrown if the MD5 digest algorithm is no available
     */
    public static UUID digestBased(String text) throws NoSuchAlgorithmException {
        assert text != null;

        final MessageDigest algo = MessageDigest.getInstance("MD5");
        algo.reset();
        algo.update(text.getBytes());

        final byte[] digest = algo.digest();

        assert digest.length == DIGEST_LEN;

        long mostSigBits = 0L;
        long leastSigBits = 0L;

        for (int i = 0; i < BYTE_SIZE; i++) {
            mostSigBits = (mostSigBits << BYTE_SIZE) | (digest[i] & BYTE_MASK);
            leastSigBits = (leastSigBits << BYTE_SIZE) | (digest[i + BYTE_SIZE] & BYTE_MASK);
        }

        return new UUID(mostSigBits, leastSigBits);
    }
}

Related

1. digest(String token)
2. digest(String type, byte[] bytes)
3. digest(String uri)
4. digest(String value, byte[] salt, int iterations)
5. digest(String value, String algorithm)
6. digestBySHA256(byte[] source)
7. digestBytes(String type, byte[]... data)
8. digestEncrypte(byte[] plainText, String algorithm)
9. digestHex(String txt)