373 lines
11 KiB
Java
373 lines
11 KiB
Java
/* UUID.java -- Class that represents a UUID object.
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Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.util;
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import java.io.Serializable;
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import java.security.MessageDigest;
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import java.security.NoSuchAlgorithmException;
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/**
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* This class represents a 128-bit UUID value.
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*
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* There are several types of UUID, and while this class can be used to store
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* them, only the Leach-Salz (variant 2) UUID specified in RFC-4122 will
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* give meaningful results from the method calls.
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* See: http://tools.ietf.org/html/4122 for the details
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*
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* The format of a Leach-Salz (variant 2) time-based (version 1) UUID
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* is as follows:
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* time_low - upper 32 bits of the most significant 64 bits,
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* this is the least-significant part of the timestamp.
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*
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* time_mid - bits 16-31 of the most significant 64 bits,
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* this is the middle portion of the timestamp.
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*
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* version - bits 8-15 of the most significant 64 bits.
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*
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* time_hi - bits 0-7 of the most significant 64 bits,
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* the most significant portion of the timestamp.
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*
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* clock_and_reserved - bits 48-63 of the least significant 64 bits.
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* a variable number of bits hold the variant
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* (see the spec)
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*
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* node identifier - bits 0-47 of the least signficant 64 bits.
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*
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* These fields are valid only for version 1, in the remaining versions,
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* only the version and variant fields are set, all others are used for data.
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*
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* @since 1.5
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* @author Sven de Marothy
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*/
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public final class UUID
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extends Object
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implements Serializable, Comparable<UUID>
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{
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private static final long serialVersionUID = -4856846361193249489L;
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/**
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* Serialized field - most significant 64 bits.
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*/
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private long mostSigBits;
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/**
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* Serialized field - least significant 64 bits.
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*/
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private long leastSigBits;
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/**
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* Random-number generator.
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*/
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private static transient Random r = new Random();
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/**
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* Constructs a new UUID.
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*
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* @since 1.5
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*/
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public UUID(long mostSigBits, long leastSigBits)
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{
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this.mostSigBits = mostSigBits;
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this.leastSigBits = leastSigBits;
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}
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/**
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* Returns the clock-sequence value of this UUID.
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* This field only exists in a time-based (version 1) UUID.
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*
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* @throws UnsupportedOperationException if the UUID type is not 1.
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* @returns an int containing the clock-sequence value.
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*/
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public int clockSequence()
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{
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if( version() != 1 )
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throw new UnsupportedOperationException("Not a type 1 UUID");
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return (int)((leastSigBits & 0x3FFF000000000000L) >> 48);
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}
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/**
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* Compare this UUID to another.
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* The comparison is performed as between two 128-bit integers.
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*
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* @return -1 if this < val, 0 if they are equal, 1 if this > val.
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*/
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public int compareTo(UUID o)
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{
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if( mostSigBits < o.mostSigBits )
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return -1;
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if( mostSigBits > o.mostSigBits )
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return 1;
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if( leastSigBits < o.leastSigBits )
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return -1;
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if( leastSigBits > o.mostSigBits )
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return 1;
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return 0;
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}
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/**
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* Compare a (UUID) object to this one
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*/
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public boolean equals(Object obj)
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{
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if( !(obj instanceof UUID ) )
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return false;
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return ( ((UUID)obj).mostSigBits == mostSigBits &&
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((UUID)obj).leastSigBits == leastSigBits );
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}
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/**
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* Creates a UUID object from a Sting representation.
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*
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* For the format of the string,
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* @see #toString()
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*
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* @return a new UUID object.
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*/
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public static UUID fromString(String name)
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{
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StringTokenizer st = new StringTokenizer( name.trim(), "-" );
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if( st.countTokens() < 5 )
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throw new IllegalArgumentException( "Incorrect UUID string"+
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" representation:"+name );
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long msb = (Long.parseLong(st.nextToken(), 16) << 32); // time low
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msb |= (Long.parseLong(st.nextToken(), 16) << 16); // time mid
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msb |= Long.parseLong(st.nextToken(), 16); // time high
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long lsb = (Long.parseLong(st.nextToken(), 16) << 48); // clock
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lsb |= Long.parseLong(st.nextToken(), 16); // node
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return new UUID(msb, lsb);
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}
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/**
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* Returns a String representation of the UUID.
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*
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* The format of the standard string representation (given in RFC4122) is:
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*
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* time-low "-" time-mid "-"
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* time-high-and-version "-"
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* clock-seq-and-reserved
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* clock-seq-low "-" node
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*
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* Where each field is represented as a hex string.
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*
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* @return the String representation.
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*/
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public String toString()
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{
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return // time-low first
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padHex( (( mostSigBits & 0xFFFFFFFF00000000L) >> 32) & 0xFFFFFFFFL, 8)
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+ "-" + // then time-mid
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padHex( (( mostSigBits & 0xFFFF0000L ) >> 16), 4 )
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+ "-" + // time-high
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padHex( ( mostSigBits & 0x0000000000000000FFFFL ), 4 )
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+ "-" + // clock (note - no reason to separate high and low here)
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padHex( (((leastSigBits & 0xFFFF000000000000L) >> 48) & 0xFFFF), 4 )
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+ "-" + // finally the node value.
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padHex(leastSigBits & 0xFFFFFFFFFFFFL, 12);
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}
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/**
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* Returns the least significant 64 bits of the UUID as a <code>long</code>.
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*/
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public long getLeastSignificantBits()
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{
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return leastSigBits;
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}
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/**
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* Returns the most significant 64 bits of the UUID as a <code>long</code>.
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*/
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public long getMostSignificantBits()
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{
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return mostSigBits;
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}
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/**
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* Returns a hash of this UUID.
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*/
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public int hashCode()
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{
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int l1 = (int)(leastSigBits & 0xFFFFFFFFL);
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int l2 = (int)((leastSigBits & 0xFFFFFFFF00000000L) >> 32);
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int m1 = (int)(mostSigBits & 0xFFFFFFFFL);
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int m2 = (int)((mostSigBits & 0xFFFFFFFF00000000L) >> 32);
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return (l1 ^ l2) ^ (m1 ^ m2);
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}
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/**
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* Creates a UUID version 3 object (name based with MD5 hashing)
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* from a series of bytes representing a name.
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*/
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public static UUID nameUUIDFromBytes(byte[] name)
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{
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long msb, lsb;
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byte[] hash;
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try
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{
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MessageDigest md5 = MessageDigest.getInstance("MD5");
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hash = md5.digest( name );
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}
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catch (NoSuchAlgorithmException e)
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{
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throw new UnsupportedOperationException("No MD5 algorithm available.");
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}
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msb = ((hash[0] & 0xFFL) << 56) | ((hash[1] & 0xFFL) << 48) |
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((hash[2] & 0xFFL) << 40) | ((hash[3] & 0xFFL) << 32) |
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((hash[4] & 0xFFL) << 24) | ((hash[5] & 0xFFL) << 16) |
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((hash[6] & 0xFFL) << 8) | (hash[7] & 0xFFL);
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lsb = ((hash[8] & 0xFFL) << 56) | ((hash[9] & 0xFFL) << 48) |
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((hash[10] & 0xFFL) << 40) | ((hash[11] & 0xFFL) << 32) |
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((hash[12] & 0xFFL) << 24) | ((hash[13] & 0xFFL) << 16) |
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((hash[14] & 0xFFL) << 8) | (hash[15] & 0xFFL);
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lsb &= 0x3FFFFFFFFFFFFFFFL;
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lsb |= 0x8000000000000000L; // set top two bits to variant 2
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msb &= 0xFFFFFFFFFFFF0FFFL;
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msb |= 0x3000; // Version 3;
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return new UUID(msb, lsb);
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}
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/**
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* Returns the 48-bit node value in a long.
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* This field only exists in a time-based (version 1) UUID.
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*
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* @throws UnsupportedOperationException if the UUID type is not 1.
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* @returns a long with the node value in the lower 48 bits.
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*/
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public long node()
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{
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if( version() != 1 )
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throw new UnsupportedOperationException("Not a type 1 UUID");
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return (leastSigBits & 0xFFFFFFFFFFFFL);
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}
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/**
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* Returns the 60-bit timestamp value of the UUID in a long.
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* This field only exists in a time-based (version 1) UUID.
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*
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* @throws UnsupportedOperationException if the UUID type is not 1.
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* @returns a long with the timestamp value.
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*/
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public long timestamp()
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{
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if( version() != 1 )
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throw new UnsupportedOperationException("Not a type 1 UUID");
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long time = (( mostSigBits & 0xFFFFFFFF00000000L) >> 32);
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time |= (( mostSigBits & 0xFFFF0000L ) << 16);
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long time_hi = ( mostSigBits & 0xFFFL );
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time |= (time_hi << 48);
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return time;
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}
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/**
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* Generate a Leach-Salz (Variant 2) randomly generated (version 4)
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* UUID.
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*
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*/
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public static UUID randomUUID()
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{
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long lsb = r.nextLong();
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long msb = r.nextLong();
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lsb &= 0x3FFFFFFFFFFFFFFFL;
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lsb |= 0x8000000000000000L; // set top two bits to variant 2
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msb &= 0xFFFFFFFFFFFF0FFFL;
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msb |= 0x4000; // Version 4;
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return new UUID( msb, lsb );
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}
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/**
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* Returns a hex String from l, padded to n spaces.
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*/
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private String padHex( long l, int n )
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{
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String s = Long.toHexString( l );
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while( s.length() < n )
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s = "0" + s;
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return s;
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}
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/**
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* Returns the variant of the UUID
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*
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* This may be:
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* 0 = Reserved for NCS backwards-compatibility
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* 2 = Leach-Salz (supports the other methods in this class)
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* 6 = Reserved for Microsoft backwards-compatibility
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* 7 = (reserved for future use)
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*/
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public int variant()
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{
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// Get the top 3 bits (not all may be part of the variant)
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int v = (int)((leastSigBits & 0xE000000000000000L) >> 61);
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if( (v & 0x04) == 0 ) // msb of the variant is 0
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return 0;
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if( (v & 0x02) == 0 ) // variant is 0 1 (Leach-Salz)
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return 2;
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return v; // 6 or 7
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}
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/**
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* Returns the version # of the UUID.
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*
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* Valid version numbers for a variant 2 UUID are:
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* 1 = Time based UUID
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* 2 = DCE security UUID
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* 3 = Name-based UUID using MD5 hashing
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* 4 = Randomly generated UUID
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* 5 = Name-based UUID using SHA-1 hashing
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*
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* @return the version number
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*/
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public int version()
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{
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return (int)((mostSigBits & 0xF000L) >> 12);
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}
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}
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