libjava/classpath/java/util/UUID.java

   1 /* UUID.java -- Class that represents a UUID object.
   2    Copyright (C) 2006  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.util;
  40
  41 import java.io.Serializable;
  42 import java.security.MessageDigest;
  43 import java.security.NoSuchAlgorithmException;
  44
  45 /**
  46  * This class represents a 128-bit UUID value.
  47  *
  48  * There are several types of UUID, and while this class can be used to store
  49  * them, only the Leach-Salz (variant 2) UUID specified in RFC-4122 will
  50  * give meaningful results from the method calls.
  51  * See: http://tools.ietf.org/html/4122 for the details
  52  *
  53  * The format of a Leach-Salz (variant 2) time-based (version 1) UUID
  54  * is as follows:
  55  * time_low - upper 32 bits of the most significant 64 bits,
  56  *            this is the least-significant part of the timestamp.
  57  *
  58  * time_mid - bits 16-31 of the most significant 64 bits,
  59  *            this is the middle portion of the timestamp.
  60  *
  61  * version  - bits 8-15 of the most significant 64 bits.
  62  *
  63  * time_hi  - bits 0-7 of the most significant 64 bits,
  64  *            the most significant portion of the timestamp.
  65  *
  66  * clock_and_reserved  - bits 48-63 of the least significant 64 bits.
  67  *                       a variable number of bits hold the variant
  68  *                       (see the spec)
  69  *
  70  * node identifier     - bits 0-47 of the least signficant 64 bits.
  71  *
  72  * These fields are valid only for version 1, in the remaining versions,
  73  * only the version and variant fields are set, all others are used for data.
  74  *
  75  * @since 1.5
  76  * @author Sven de Marothy
  77  */
  78 public final class UUID
  79   extends Object
  80   implements Serializable, Comparable<UUID>
  81 {
  82   private static final long serialVersionUID = -4856846361193249489L;
  83
  84   /**
  85    * Serialized field - most significant 64 bits.
  86    */
  87   private long mostSigBits;
  88
  89   /**
  90    * Serialized field - least significant 64 bits.
  91    */
  92   private long leastSigBits;
  93
  94   /**
  95    * Random-number generator.
  96    */
  97   private static transient Random r = new Random();
  98
  99   /**
 100    * Constructs a new UUID.
 101    *
 102    * @since 1.5
 103    */
 104   public UUID(long mostSigBits, long leastSigBits)
 105   {
 106     this.mostSigBits = mostSigBits;
 107     this.leastSigBits = leastSigBits;
 108   }
 109
 110   /**
 111    * Returns the clock-sequence value of this UUID.
 112    * This field only exists in a time-based (version 1) UUID.
 113    *
 114    * @throws UnsupportedOperationException if the UUID type is not 1.
 115    * @returns an int containing the clock-sequence value.
 116    */
 117   public int clockSequence()
 118   {
 119     if( version() != 1 )
 120       throw new UnsupportedOperationException("Not a type 1 UUID");
 121     return (int)((leastSigBits & 0x3FFF000000000000L) >> 48);
 122   }
 123
 124   /**
 125    * Compare this UUID to another.
 126    * The comparison is performed as between two 128-bit integers.
 127    *
 128    * @return -1 if this < val, 0 if they are equal, 1 if this > val.
 129    */
 130   public int compareTo(UUID o)
 131   {
 132     if( mostSigBits < o.mostSigBits )
 133       return -1;
 134     if( mostSigBits > o.mostSigBits )
 135       return 1;
 136     if( leastSigBits < o.leastSigBits )
 137       return -1;
 138     if( leastSigBits > o.mostSigBits )
 139       return 1;
 140     return 0;
 141   }
 142
 143   /**
 144    * Compare a (UUID) object to this one
 145    */
 146   public boolean equals(Object obj)
 147   {
 148     if( !(obj instanceof UUID ) )
 149       return false;
 150     return ( ((UUID)obj).mostSigBits == mostSigBits &&
 151              ((UUID)obj).leastSigBits == leastSigBits );
 152   }
 153
 154   /**
 155    * Creates a UUID object from a Sting representation.
 156    *
 157    * For the format of the string,
 158    * @see #toString()
 159    *
 160    * @return a new UUID object.
 161    */
 162   public static UUID fromString(String name)
 163   {
 164     StringTokenizer st = new StringTokenizer( name.trim(), "-" );
 165     if( st.countTokens() < 5 )
 166       throw new IllegalArgumentException( "Incorrect UUID string"+
 167                                           " representation:"+name );
 168
 169     long msb = (Long.parseLong(st.nextToken(), 16) << 32); // time low
 170     msb |= (Long.parseLong(st.nextToken(), 16) << 16); // time mid
 171     msb |= Long.parseLong(st.nextToken(), 16); // time high
 172
 173     long lsb = (Long.parseLong(st.nextToken(), 16) << 48); // clock
 174     lsb |= Long.parseLong(st.nextToken(), 16); // node
 175
 176     return new UUID(msb, lsb);
 177   }
 178
 179   /**
 180    * Returns a String representation of the UUID.
 181    *
 182    * The format of the standard string representation (given in RFC4122) is:
 183    *
 184    * time-low "-" time-mid "-"
 185    * time-high-and-version "-"
 186    * clock-seq-and-reserved
 187    * clock-seq-low "-" node
 188    *
 189    * Where each field is represented as a hex string.
 190    *
 191    * @return the String representation.
 192    */
 193   public String toString()
 194   {
 195     return // time-low first
 196       padHex( (( mostSigBits & 0xFFFFFFFF00000000L) >> 32) & 0xFFFFFFFFL, 8)
 197       + "-" + // then time-mid
 198       padHex( (( mostSigBits & 0xFFFF0000L ) >> 16), 4 )
 199       + "-" + // time-high
 200       padHex( ( mostSigBits & 0x0000000000000000FFFFL ), 4 )
 201       + "-" + // clock (note - no reason to separate high and low here)
 202       padHex( (((leastSigBits & 0xFFFF000000000000L) >> 48) & 0xFFFF), 4 )
 203       + "-" + // finally the node value.
 204       padHex(leastSigBits & 0xFFFFFFFFFFFFL, 12);
 205   }
 206
 207   /**
 208    * Returns the least significant 64 bits of the UUID as a <code>long</code>.
 209    */
 210   public long getLeastSignificantBits()
 211   {
 212     return leastSigBits;
 213   }
 214
 215   /**
 216    * Returns the most significant 64 bits of the UUID as a <code>long</code>.
 217    */
 218   public long getMostSignificantBits()
 219   {
 220     return mostSigBits;
 221   }
 222
 223   /**
 224    * Returns a hash of this UUID.
 225    */
 226   public int hashCode()
 227   {
 228     int l1 = (int)(leastSigBits & 0xFFFFFFFFL);
 229     int l2 = (int)((leastSigBits & 0xFFFFFFFF00000000L) >> 32);
 230     int m1 = (int)(mostSigBits & 0xFFFFFFFFL);
 231     int m2 = (int)((mostSigBits & 0xFFFFFFFF00000000L) >> 32);
 232
 233     return (l1 ^ l2) ^ (m1 ^ m2);
 234   }
 235
 236   /**
 237    * Creates a UUID version 3 object (name based with MD5 hashing)
 238    * from a series of bytes representing a name.
 239    */
 240   public static UUID nameUUIDFromBytes(byte[] name)
 241   {
 242     long msb, lsb;
 243     byte[] hash;
 244
 245     try
 246       {
 247         MessageDigest md5 = MessageDigest.getInstance("MD5");
 248         hash = md5.digest( name );
 249       }
 250     catch (NoSuchAlgorithmException e)
 251       {
 252         throw new UnsupportedOperationException("No MD5 algorithm available.");
 253       }
 254
 255     msb = ((hash[0] & 0xFFL) << 56) | ((hash[1] & 0xFFL) << 48) |
 256       ((hash[2] & 0xFFL) << 40) | ((hash[3] & 0xFFL) << 32) |
 257       ((hash[4] & 0xFFL) << 24) | ((hash[5] & 0xFFL) << 16) |
 258       ((hash[6] & 0xFFL) << 8) | (hash[7] & 0xFFL);
 259
 260     lsb = ((hash[8] & 0xFFL) << 56) | ((hash[9] & 0xFFL) << 48) |
 261       ((hash[10] & 0xFFL) << 40) | ((hash[11] & 0xFFL) << 32) |
 262       ((hash[12] & 0xFFL) << 24) | ((hash[13] & 0xFFL) << 16) |
 263       ((hash[14] & 0xFFL) << 8) | (hash[15] & 0xFFL);
 264
 265     lsb &= 0x3FFFFFFFFFFFFFFFL;
 266     lsb |= 0x8000000000000000L; // set top two bits to variant 2
 267
 268     msb &= 0xFFFFFFFFFFFF0FFFL;
 269     msb |= 0x3000; // Version 3;
 270
 271     return new UUID(msb, lsb);
 272   }
 273
 274   /**
 275    * Returns the 48-bit node value in a long.
 276    * This field only exists in a time-based (version 1) UUID.
 277    *
 278    * @throws UnsupportedOperationException if the UUID type is not 1.
 279    * @returns a long with the node value in the lower 48 bits.
 280    */
 281   public long node()
 282   {
 283     if( version() != 1 )
 284       throw new UnsupportedOperationException("Not a type 1 UUID");
 285     return (leastSigBits & 0xFFFFFFFFFFFFL);
 286   }
 287
 288   /**
 289    * Returns the 60-bit timestamp value of the UUID in a long.
 290    * This field only exists in a time-based (version 1) UUID.
 291    *
 292    * @throws UnsupportedOperationException if the UUID type is not 1.
 293    * @returns a long with the timestamp value.
 294    */
 295   public long timestamp()
 296   {
 297     if( version() != 1 )
 298       throw new UnsupportedOperationException("Not a type 1 UUID");
 299     long time = (( mostSigBits & 0xFFFFFFFF00000000L) >> 32);
 300     time |= (( mostSigBits & 0xFFFF0000L ) << 16);
 301     long time_hi = ( mostSigBits & 0xFFFL );
 302     time |= (time_hi << 48);
 303     return time;
 304   }
 305
 306   /**
 307    * Generate a Leach-Salz (Variant 2) randomly generated (version 4)
 308    * UUID.
 309    *
 310    */
 311   public static UUID randomUUID()
 312   {
 313     long lsb = r.nextLong();
 314     long msb = r.nextLong();
 315
 316     lsb &= 0x3FFFFFFFFFFFFFFFL;
 317     lsb |= 0x8000000000000000L; // set top two bits to variant 2
 318
 319     msb &= 0xFFFFFFFFFFFF0FFFL;
 320     msb |= 0x4000; // Version 4;
 321
 322     return new UUID( msb, lsb );
 323   }
 324
 325   /**
 326    * Returns a hex String from l, padded to n spaces.
 327    */
 328   private String padHex( long l, int n )
 329   {
 330     String s = Long.toHexString( l );
 331     while( s.length() < n )
 332       s = "0" + s;
 333     return s;
 334   }
 335
 336   /**
 337    * Returns the variant of the UUID
 338    *
 339    * This may be:
 340    * 0 = Reserved for NCS backwards-compatibility
 341    * 2 = Leach-Salz (supports the other methods in this class)
 342    * 6 = Reserved for Microsoft backwards-compatibility
 343    * 7 = (reserved for future use)
 344    */
 345   public int variant()
 346   {
 347     // Get the top 3 bits (not all may be part of the variant)
 348     int v = (int)((leastSigBits & 0xE000000000000000L) >> 61);
 349     if( (v & 0x04) == 0 ) // msb of the variant is 0
 350       return 0;
 351     if( (v & 0x02) == 0 ) // variant is 0 1 (Leach-Salz)
 352       return 2;
 353     return v; // 6 or 7
 354   }
 355
 356   /**
 357    * Returns the version # of the UUID.
 358    *
 359    * Valid version numbers for a variant 2 UUID are:
 360    * 1 = Time based UUID
 361    * 2 = DCE security UUID
 362    * 3 = Name-based UUID using MD5 hashing
 363    * 4 = Randomly generated UUID
 364    * 5 = Name-based UUID using SHA-1 hashing
 365    *
 366    * @return the version number
 367    */
 368   public int version()
 369   {
 370     return (int)((mostSigBits & 0xF000L) >> 12);
 371   }
 372 }