constants.java

jsr170接口的java实现。是个apache的开源项目。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jackrabbit.uuid;

/**
 * <p>Constant values commonly needed in the uuid classes.</p>
 * <p/>
 * <p>Copied from the Jakarta Commons-Id project</p>
 * <p/>
 * todo remove and use official commons-id release as soon as it is available
 */
public interface Constants {

    //** Magic number constants
    /**
     * Bits in a UUID.
     */
    int UUID_BIT_LENGTH = 128;

    /**
     * Number of bytes in a UUID.
     */
    int UUID_BYTE_LENGTH = 16;


    //** Formatting and validation constants
    /**
     * Chars in a UUID String.
     */
    int UUID_UNFORMATTED_LENGTH = 32;

    /**
     * Chars in a UUID String.
     */
    int UUID_FORMATTED_LENGTH = 36;

    /**
     * Token length of '-' separated tokens.
     */
    int TOKENS_IN_UUID = 5;

    /**
     * Array to check tokenized UUID's segment lengths
     */
    int[] TOKEN_LENGTHS = {8, 4, 4, 4, 12};

    /**
     * Insertion point 1 for dashes in the string format
     */
    int FORMAT_POSITION1 = 8;

    /**
     * Insertion point 2 for dashes in the string format
     */
    int FORMAT_POSITION2 = 13;

    /**
     * Insertion point 3 for dashes in the string format
     */
    int FORMAT_POSITION3 = 18;

    /**
     * Insertion point 4 for dashes in the string format
     */
    int FORMAT_POSITION4 = 23;

    /**
     * The string prefix for a urn UUID identifier.
     */
    String URN_PREFIX = "urn:uuid:";


    //** UUID Variant QueryConstants
    /**
     * UUID variant bits described in the IETF Draft MSB order,
     * this is the "Reserved, NCS backward compatibility field" 0 x x with unknown bits as 0
     */
    int VARIANT_NCS_COMPAT = 0;

    /**
     * UUID variant bits described in the IETF Draft MSB order,
     * this is the IETF Draft memo variant field 1 0 x with unknown bits as 0
     */
    int VARIANT_IETF_DRAFT = 2;

    /**
     * UUID variant bits described in the IETF Draft MSB order,
     * this is the IETF Draft "Microsoft Corporation" field variant 1 1 0 x with unknown bits as 0
     */
    int VARIANT_MS = (byte) 6;

    /**
     * UUID variant bits described in the IETF Draft MSB order,
     * this is the "Future Reserved variant 1 1 1 x with unknown bits as 0
     */
    int VARIANT_FUTURE = 7;


    //** UUID Version QueryConstants
    /**
     * Version one constant for UUID version one of four
     */
    int VERSION_ONE = 1;

    /**
     * Version two constant for UUID version two of four
     */
    int VERSION_TWO = 2;

    /**
     * Version three constant for UUID version three of four
     */
    int VERSION_THREE = 3;

    /**
     * Version four constant for UUID version four of four
     */
    int VERSION_FOUR = 4;

    //** Exception message constants
    /**
     * Message indicating this is not a version one UUID
     */
    String WRONG_VAR_VER_MSG = "Not a ietf variant 2 or version 1 (time-based UUID)";

    // ** Array positions and lengths of UUID fields ** //
    /**
     * Byte length of time low field
     */
    int TIME_LOW_BYTE_LEN = 4;
    /**
     * Byte length of time low field
     */
    int TIME_MID_BYTE_LEN = 2;
    /**
     * Byte length of time low field
     */
    int TIME_HI_BYTE_LEN = 2;
    /**
     * Timestamp byte[] position of time low field
     */
    int TIME_LOW_TS_POS = 4;
    /**
     * Timestamp byte[]  position mid field
     */
    int TIME_MID_TS_POS = 2;
    /**
     * Timestamp byte[]  position hi field
     */
    int TIME_HI_TS_POS = 0;
    /**
     * uuid array position start of time low field
     */
    int TIME_LOW_START_POS = 0;
    /**
     * uuid array position start of mid field
     */
    int TIME_MID_START_POS = 4;
    /**
     * uuid array position start of hi field
     */
    int TIME_HI_START_POS = 6;
    /**
     * Byte position of the clock sequence and reserved field
     */
    short TIME_HI_AND_VERSION_BYTE_6 = 6;
    /**
     * Byte position of the clock sequence and reserved field
     */
    short CLOCK_SEQ_HI_AND_RESERVED_BYTE_8 = 8;

    /**
     * XXX added by [e-mail]:
     * hexdigits for converting numerics to hex
     */
    char[] hexDigits = "0123456789abcdef".toCharArray();
}