uuid.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions are met:
 *  
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  
 *  2. Redistributions in binary form must reproduce the above copyright notice, 
 *     this list of conditions and the following disclaimer in the documentation 
 *     and/or other materials provided with the distribution.
 *  
 *  3. The end-user documentation included with the redistribution, if any, must 
 *     include the following acknowledgment: "This product includes software 
 *     developed by Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     Alternately, this acknowledgment may appear in the software itself, if 
 *     and wherever such third-party acknowledgments normally appear.
 *  
 *  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must 
 *     not be used to endorse or promote products derived from this software 
 *     without prior written permission. For written permission, please contact 
 *     Project JXTA at http://www.jxta.org.
 *  
 *  5. Products derived from this software may not be called "JXTA", nor may 
 *     "JXTA" appear in their name, without prior written permission of Sun.
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 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
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 *  JXTA is a registered trademark of Sun Microsystems, Inc. in the United 
 *  States and other countries.
 *  
 *  Please see the license information page at :
 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
 *  the license in source files.
 *  
 *  ====================================================================
 *  
 *  This software consists of voluntary contributions made by many individuals 
 *  on behalf of Project JXTA. For more information on Project JXTA, please see 
 *  http://www.jxta.org.
 *  
 *  This license is based on the BSD license adopted by the Apache Foundation. 
 */

package net.jxta.impl.id.UUID;


import java.io.Serializable;


/**
 * A <code>UUID</code> is a 128-bit universally unique identifier.
 * The most significant long can be decomposed into the following
 * unsigned fields:
 * <pre>
 * 0xFFFFFFFF00000000 time_low
 * 0x00000000FFFF0000 time_mid
 * 0x000000000000F000 version
 * 0x0000000000000FFF time_hi
 * </pre>
 * <p/>The least significant long can be decomposed into the following
 * unsigned fields:
 * <pre>
 * 0xC000000000000000 variant
 * 0x3FFF000000000000 clock_seq
 * 0x0000FFFFFFFFFFFF node
 * </pre>
 * <p/>The variant field must be 0x2. The version field must be either 0x1 or 0x4.
 *
 * <p/>If the version field is 0x4, then the most significant bit of the node
 * field must be set to 1, and the remaining fields are set to values
 * produced by a cryptographically strong pseudo-random number generator.
 *
 * <p/>If the version field is 0x1, then the node field is set to an IEEE 802
 * address (MAC), the clock_seq field is set to a 14-bit random number, and the
 * time_low, time_mid, and time_hi fields are set to the least, middle and
 * most significant bits (respectively) of a 60-bit timestamp measured in
 * 100-nanosecond units since midnight, October 15, 1582 UTC.
 *
 * @see         net.jxta.impl.id.UUID.IDFormat
 * @see         net.jxta.impl.id.UUID.UUIDFactory
 * @see "<i>Information Technology - Open Systems Interconnection - Remote Procedure Call (RPC)</i>, ISO 11578:1996"
 * @see <a href="http://www.opengroup.org/onlinepubs/9629399/apdxa.htm" target="_blank"><i>The Open Group - DCE 1.1 Remote Procedure Call (RPC) : Appendix A - Universal Unique Identifier</i></a>
 *
 */
public final class UUID implements Serializable {

    /**
     *  The null UUID. Useful for comparisons.
     */
    public static final UUID nullUUID = new UUID(0L, 0L);

    /**
     * The most significant 64 bits.
     */
    private long mostSig;

    /**
     * The least significant 64 bits.
     */
    private long leastSig;

    /**
     * Simple constructor. This constructor does not check to ensure that the
     * values provided produce a valid UUID.
     *
     * @param mostSig the most significant 64 bits
     * @param leastSig the least significant 64 bits
     */
    public UUID(long mostSig, long leastSig) {
        this.mostSig = mostSig;
        this.leastSig = leastSig;
    }

    /**
     * Simple constructor. This constructor does not check to ensure that the
     * values provided produce a valid UUID.
     *
     * @param bytes the 128 bits of
     */
    public UUID(byte[] bytes) {
        if (bytes.length != 16) {
            throw new IllegalArgumentException("bytes must be 16 bytes in length");
        }

        long mostSig = 0;

        for (int i = 0; i < 8; i++) {
            mostSig = (mostSig << 8) | (bytes[i] & 0xff);
        }

        long leastSig = 0;

        for (int i = 8; i < 16; i++) {
            leastSig = (leastSig << 8) | (bytes[i] & 0xff);
        }

        this.mostSig = mostSig;
        this.leastSig = leastSig;
    }

    public UUID(String uuid) {
        if (36 != uuid.length()) {
            throw new IllegalArgumentException("uuid must be 36 characters in length");
        }

        byte bytes[] = new byte[16];

        boolean hi = true;

        for (int eachChar = 0, offset = 0; eachChar < 36; eachChar++) {
            char aChar = uuid.charAt(eachChar);

            switch (eachChar) {
            case 8:
            case 13:
            case 18:
            case 23:
                if ('-' != uuid.charAt(eachChar)) {
                    throw new IllegalArgumentException("uuid has an illegal character at position " + eachChar);
                }
                break;

            default:
                aChar = Character.toLowerCase(aChar);

                int aNibble;

                if (('0' <= aChar) && ('9' >= aChar)) {
                    aNibble = aChar - '0';
                } else if (('a' <= aChar) && ('f' >= aChar)) {
                    aNibble = aChar - 'a' + 10;
                } else {
                    throw new IllegalArgumentException("uuid has an illegal character at position " + eachChar);
                }

                if (hi) {
                    aNibble <<= 4;
                }

                bytes[offset] |= aNibble;

                if (!hi) {
                    offset++;
                }

                hi = !hi;
            }
        }

        mostSig = 0;
        for (int i = 0; i < 8; i++) {
            mostSig = (mostSig << 8) | (bytes[i] & 0xff);
        }

        leastSig = 0;
        for (int i = 8; i < 16; i++) {
            leastSig = (leastSig << 8) | (bytes[i] & 0xff);
        }
    }

    /**
     * Returns the most significant 64 bits of the UUID.
     *
     * @return long return most significant bits
     */
    public long getMostSignificantBits() {
        return mostSig;
    }

    /**
     * Returns the least significant 64 bits of the UUID.
     *
     * @return long least significant bits
     */
    public long getLeastSignificantBits() {
        return leastSig;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        return (int) ((mostSig >> 32) ^ mostSig ^ (leastSig >> 32) ^ leastSig);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(Object target) {
        if (this == target) {
            return true;
        }

        if (target instanceof UUID) {
            return equals((UUID) target);
        } else {
            return false;
        }
    }

    /**
     * UUIDs are equal if they represent the same 128-bit value.
     *
     * @param sid UUID seed
     * @return boolean true if equals
     */
    public boolean equals(UUID sid) {
        if (null == sid) {
            return false;
        }

        return (mostSig == sid.mostSig && leastSig == sid.leastSig);
    }

    /**
     * Returns a 36-character string of six fields separated by hyphens,
     * with each field represented in lowercase hexadecimal with the same
     * number of digits as in the field. The order of fields is: time_low,
     * time_mid, version and time_hi treated as a single field, variant and
     * clock_seq treated as a single field, and node.
     *
     * ie. XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
     *
     * @return String return value
     */
    @Override
    public String toString() {
        return (digits(mostSig >> 32, 8) + "-" + digits(mostSig >> 16, 4) + "-" + digits(mostSig, 4) + "-"
                + digits(leastSig >> 48, 4) + "-" + digits(leastSig, 12));
    }

    /**
     * Returns val represented by the specified number of hex digits
     *
     * @param val value
     * @param digits
     * @return String return value
     */
    private static String digits(long val, int digits) {
        long hi = 1L << (digits * 4);

        return Long.toHexString(hi | (val & (hi - 1))).substring(1);
    }
}