| /* |
| * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.util; |
| |
| import java.security.*; |
| |
| /** |
| * A class that represents an immutable universally unique identifier (UUID). |
| * A UUID represents a 128-bit value. |
| * |
| * <p> There exist different variants of these global identifiers. The methods |
| * of this class are for manipulating the Leach-Salz variant, although the |
| * constructors allow the creation of any variant of UUID (described below). |
| * |
| * <p> The layout of a variant 2 (Leach-Salz) UUID is as follows: |
| * |
| * The most significant long consists of the following unsigned fields: |
| * <pre> |
| * 0xFFFFFFFF00000000 time_low |
| * 0x00000000FFFF0000 time_mid |
| * 0x000000000000F000 version |
| * 0x0000000000000FFF time_hi |
| * </pre> |
| * The least significant long consists of the following unsigned fields: |
| * <pre> |
| * 0xC000000000000000 variant |
| * 0x3FFF000000000000 clock_seq |
| * 0x0000FFFFFFFFFFFF node |
| * </pre> |
| * |
| * <p> The variant field contains a value which identifies the layout of the |
| * {@code UUID}. The bit layout described above is valid only for a {@code |
| * UUID} with a variant value of 2, which indicates the Leach-Salz variant. |
| * |
| * <p> The version field holds a value that describes the type of this {@code |
| * UUID}. There are four different basic types of UUIDs: time-based, DCE |
| * security, name-based, and randomly generated UUIDs. These types have a |
| * version value of 1, 2, 3 and 4, respectively. |
| * |
| * <p> For more information including algorithms used to create {@code UUID}s, |
| * see <a href="http://www.ietf.org/rfc/rfc4122.txt"> <i>RFC 4122: A |
| * Universally Unique IDentifier (UUID) URN Namespace</i></a>, section 4.2 |
| * "Algorithms for Creating a Time-Based UUID". |
| * |
| * @since 1.5 |
| */ |
| public final class UUID implements java.io.Serializable, Comparable<UUID> { |
| |
| /** |
| * Explicit serialVersionUID for interoperability. |
| */ |
| private static final long serialVersionUID = -4856846361193249489L; |
| |
| /* |
| * The most significant 64 bits of this UUID. |
| * |
| * @serial |
| */ |
| private final long mostSigBits; |
| |
| /* |
| * The least significant 64 bits of this UUID. |
| * |
| * @serial |
| */ |
| private final long leastSigBits; |
| |
| /* |
| * The random number generator used by this class to create random |
| * based UUIDs. In a holder class to defer initialization until needed. |
| */ |
| private static class Holder { |
| static final SecureRandom numberGenerator = new SecureRandom(); |
| } |
| |
| // Constructors and Factories |
| |
| /* |
| * Private constructor which uses a byte array to construct the new UUID. |
| */ |
| private UUID(byte[] data) { |
| long msb = 0; |
| long lsb = 0; |
| assert data.length == 16 : "data must be 16 bytes in length"; |
| for (int i=0; i<8; i++) |
| msb = (msb << 8) | (data[i] & 0xff); |
| for (int i=8; i<16; i++) |
| lsb = (lsb << 8) | (data[i] & 0xff); |
| this.mostSigBits = msb; |
| this.leastSigBits = lsb; |
| } |
| |
| /** |
| * Constructs a new {@code UUID} using the specified data. {@code |
| * mostSigBits} is used for the most significant 64 bits of the {@code |
| * UUID} and {@code leastSigBits} becomes the least significant 64 bits of |
| * the {@code UUID}. |
| * |
| * @param mostSigBits |
| * The most significant bits of the {@code UUID} |
| * |
| * @param leastSigBits |
| * The least significant bits of the {@code UUID} |
| */ |
| public UUID(long mostSigBits, long leastSigBits) { |
| this.mostSigBits = mostSigBits; |
| this.leastSigBits = leastSigBits; |
| } |
| |
| /** |
| * Static factory to retrieve a type 4 (pseudo randomly generated) UUID. |
| * |
| * The {@code UUID} is generated using a cryptographically strong pseudo |
| * random number generator. |
| * |
| * @return A randomly generated {@code UUID} |
| */ |
| public static UUID randomUUID() { |
| SecureRandom ng = Holder.numberGenerator; |
| |
| byte[] randomBytes = new byte[16]; |
| ng.nextBytes(randomBytes); |
| randomBytes[6] &= 0x0f; /* clear version */ |
| randomBytes[6] |= 0x40; /* set to version 4 */ |
| randomBytes[8] &= 0x3f; /* clear variant */ |
| randomBytes[8] |= 0x80; /* set to IETF variant */ |
| return new UUID(randomBytes); |
| } |
| |
| /** |
| * Static factory to retrieve a type 3 (name based) {@code UUID} based on |
| * the specified byte array. |
| * |
| * @param name |
| * A byte array to be used to construct a {@code UUID} |
| * |
| * @return A {@code UUID} generated from the specified array |
| */ |
| public static UUID nameUUIDFromBytes(byte[] name) { |
| MessageDigest md; |
| try { |
| md = MessageDigest.getInstance("MD5"); |
| } catch (NoSuchAlgorithmException nsae) { |
| throw new InternalError("MD5 not supported"); |
| } |
| byte[] md5Bytes = md.digest(name); |
| md5Bytes[6] &= 0x0f; /* clear version */ |
| md5Bytes[6] |= 0x30; /* set to version 3 */ |
| md5Bytes[8] &= 0x3f; /* clear variant */ |
| md5Bytes[8] |= 0x80; /* set to IETF variant */ |
| return new UUID(md5Bytes); |
| } |
| |
| /** |
| * Creates a {@code UUID} from the string standard representation as |
| * described in the {@link #toString} method. |
| * |
| * @param name |
| * A string that specifies a {@code UUID} |
| * |
| * @return A {@code UUID} with the specified value |
| * |
| * @throws IllegalArgumentException |
| * If name does not conform to the string representation as |
| * described in {@link #toString} |
| * |
| */ |
| public static UUID fromString(String name) { |
| String[] components = name.split("-"); |
| if (components.length != 5) |
| throw new IllegalArgumentException("Invalid UUID string: "+name); |
| for (int i=0; i<5; i++) |
| components[i] = "0x"+components[i]; |
| |
| long mostSigBits = Long.decode(components[0]).longValue(); |
| mostSigBits <<= 16; |
| mostSigBits |= Long.decode(components[1]).longValue(); |
| mostSigBits <<= 16; |
| mostSigBits |= Long.decode(components[2]).longValue(); |
| |
| long leastSigBits = Long.decode(components[3]).longValue(); |
| leastSigBits <<= 48; |
| leastSigBits |= Long.decode(components[4]).longValue(); |
| |
| return new UUID(mostSigBits, leastSigBits); |
| } |
| |
| // Field Accessor Methods |
| |
| /** |
| * Returns the least significant 64 bits of this UUID's 128 bit value. |
| * |
| * @return The least significant 64 bits of this UUID's 128 bit value |
| */ |
| public long getLeastSignificantBits() { |
| return leastSigBits; |
| } |
| |
| /** |
| * Returns the most significant 64 bits of this UUID's 128 bit value. |
| * |
| * @return The most significant 64 bits of this UUID's 128 bit value |
| */ |
| public long getMostSignificantBits() { |
| return mostSigBits; |
| } |
| |
| /** |
| * The version number associated with this {@code UUID}. The version |
| * number describes how this {@code UUID} was generated. |
| * |
| * The version number has the following meaning: |
| * <p><ul> |
| * <li>1 Time-based UUID |
| * <li>2 DCE security UUID |
| * <li>3 Name-based UUID |
| * <li>4 Randomly generated UUID |
| * </ul> |
| * |
| * @return The version number of this {@code UUID} |
| */ |
| public int version() { |
| // Version is bits masked by 0x000000000000F000 in MS long |
| return (int)((mostSigBits >> 12) & 0x0f); |
| } |
| |
| /** |
| * The variant number associated with this {@code UUID}. The variant |
| * number describes the layout of the {@code UUID}. |
| * |
| * The variant number has the following meaning: |
| * <p><ul> |
| * <li>0 Reserved for NCS backward compatibility |
| * <li>2 <a href="http://www.ietf.org/rfc/rfc4122.txt">IETF RFC 4122</a> |
| * (Leach-Salz), used by this class |
| * <li>6 Reserved, Microsoft Corporation backward compatibility |
| * <li>7 Reserved for future definition |
| * </ul> |
| * |
| * @return The variant number of this {@code UUID} |
| */ |
| public int variant() { |
| // This field is composed of a varying number of bits. |
| // 0 - - Reserved for NCS backward compatibility |
| // 1 0 - The IETF aka Leach-Salz variant (used by this class) |
| // 1 1 0 Reserved, Microsoft backward compatibility |
| // 1 1 1 Reserved for future definition. |
| return (int) ((leastSigBits >>> (64 - (leastSigBits >>> 62))) |
| & (leastSigBits >> 63)); |
| } |
| |
| /** |
| * The timestamp value associated with this UUID. |
| * |
| * <p> The 60 bit timestamp value is constructed from the time_low, |
| * time_mid, and time_hi fields of this {@code UUID}. The resulting |
| * timestamp is measured in 100-nanosecond units since midnight, |
| * October 15, 1582 UTC. |
| * |
| * <p> The timestamp value is only meaningful in a time-based UUID, which |
| * has version type 1. If this {@code UUID} is not a time-based UUID then |
| * this method throws UnsupportedOperationException. |
| * |
| * @throws UnsupportedOperationException |
| * If this UUID is not a version 1 UUID |
| */ |
| public long timestamp() { |
| if (version() != 1) { |
| throw new UnsupportedOperationException("Not a time-based UUID"); |
| } |
| |
| return (mostSigBits & 0x0FFFL) << 48 |
| | ((mostSigBits >> 16) & 0x0FFFFL) << 32 |
| | mostSigBits >>> 32; |
| } |
| |
| /** |
| * The clock sequence value associated with this UUID. |
| * |
| * <p> The 14 bit clock sequence value is constructed from the clock |
| * sequence field of this UUID. The clock sequence field is used to |
| * guarantee temporal uniqueness in a time-based UUID. |
| * |
| * <p> The {@code clockSequence} value is only meaningful in a time-based |
| * UUID, which has version type 1. If this UUID is not a time-based UUID |
| * then this method throws UnsupportedOperationException. |
| * |
| * @return The clock sequence of this {@code UUID} |
| * |
| * @throws UnsupportedOperationException |
| * If this UUID is not a version 1 UUID |
| */ |
| public int clockSequence() { |
| if (version() != 1) { |
| throw new UnsupportedOperationException("Not a time-based UUID"); |
| } |
| |
| return (int)((leastSigBits & 0x3FFF000000000000L) >>> 48); |
| } |
| |
| /** |
| * The node value associated with this UUID. |
| * |
| * <p> The 48 bit node value is constructed from the node field of this |
| * UUID. This field is intended to hold the IEEE 802 address of the machine |
| * that generated this UUID to guarantee spatial uniqueness. |
| * |
| * <p> The node value is only meaningful in a time-based UUID, which has |
| * version type 1. If this UUID is not a time-based UUID then this method |
| * throws UnsupportedOperationException. |
| * |
| * @return The node value of this {@code UUID} |
| * |
| * @throws UnsupportedOperationException |
| * If this UUID is not a version 1 UUID |
| */ |
| public long node() { |
| if (version() != 1) { |
| throw new UnsupportedOperationException("Not a time-based UUID"); |
| } |
| |
| return leastSigBits & 0x0000FFFFFFFFFFFFL; |
| } |
| |
| // Object Inherited Methods |
| |
| /** |
| * Returns a {@code String} object representing this {@code UUID}. |
| * |
| * <p> The UUID string representation is as described by this BNF: |
| * <blockquote><pre> |
| * {@code |
| * UUID = <time_low> "-" <time_mid> "-" |
| * <time_high_and_version> "-" |
| * <variant_and_sequence> "-" |
| * <node> |
| * time_low = 4*<hexOctet> |
| * time_mid = 2*<hexOctet> |
| * time_high_and_version = 2*<hexOctet> |
| * variant_and_sequence = 2*<hexOctet> |
| * node = 6*<hexOctet> |
| * hexOctet = <hexDigit><hexDigit> |
| * hexDigit = |
| * "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" |
| * | "a" | "b" | "c" | "d" | "e" | "f" |
| * | "A" | "B" | "C" | "D" | "E" | "F" |
| * }</pre></blockquote> |
| * |
| * @return A string representation of this {@code UUID} |
| */ |
| public String toString() { |
| return (digits(mostSigBits >> 32, 8) + "-" + |
| digits(mostSigBits >> 16, 4) + "-" + |
| digits(mostSigBits, 4) + "-" + |
| digits(leastSigBits >> 48, 4) + "-" + |
| digits(leastSigBits, 12)); |
| } |
| |
| /** Returns val represented by the specified number of hex digits. */ |
| private static String digits(long val, int digits) { |
| long hi = 1L << (digits * 4); |
| return Long.toHexString(hi | (val & (hi - 1))).substring(1); |
| } |
| |
| /** |
| * Returns a hash code for this {@code UUID}. |
| * |
| * @return A hash code value for this {@code UUID} |
| */ |
| public int hashCode() { |
| long hilo = mostSigBits ^ leastSigBits; |
| return ((int)(hilo >> 32)) ^ (int) hilo; |
| } |
| |
| /** |
| * Compares this object to the specified object. The result is {@code |
| * true} if and only if the argument is not {@code null}, is a {@code UUID} |
| * object, has the same variant, and contains the same value, bit for bit, |
| * as this {@code UUID}. |
| * |
| * @param obj |
| * The object to be compared |
| * |
| * @return {@code true} if the objects are the same; {@code false} |
| * otherwise |
| */ |
| public boolean equals(Object obj) { |
| if ((null == obj) || (obj.getClass() != UUID.class)) |
| return false; |
| UUID id = (UUID)obj; |
| return (mostSigBits == id.mostSigBits && |
| leastSigBits == id.leastSigBits); |
| } |
| |
| // Comparison Operations |
| |
| /** |
| * Compares this UUID with the specified UUID. |
| * |
| * <p> The first of two UUIDs is greater than the second if the most |
| * significant field in which the UUIDs differ is greater for the first |
| * UUID. |
| * |
| * @param val |
| * {@code UUID} to which this {@code UUID} is to be compared |
| * |
| * @return -1, 0 or 1 as this {@code UUID} is less than, equal to, or |
| * greater than {@code val} |
| * |
| */ |
| public int compareTo(UUID val) { |
| // The ordering is intentionally set up so that the UUIDs |
| // can simply be numerically compared as two numbers |
| return (this.mostSigBits < val.mostSigBits ? -1 : |
| (this.mostSigBits > val.mostSigBits ? 1 : |
| (this.leastSigBits < val.leastSigBits ? -1 : |
| (this.leastSigBits > val.leastSigBits ? 1 : |
| 0)))); |
| } |
| } |
