001: /*
002: * ====================================================================
003: * JAFFA - Java Application Framework For All
004: *
005: * Copyright (C) 2002 JAFFA Development Group
006: *
007: * This library is free software; you can redistribute it and/or
008: * modify it under the terms of the GNU Lesser General Public
009: * License as published by the Free Software Foundation; either
010: * version 2.1 of the License, or (at your option) any later version.
011: *
012: * This library is distributed in the hope that it will be useful,
013: * but WITHOUT ANY WARRANTY; without even the implied warranty of
014: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015: * Lesser General Public License for more details.
016: *
017: * You should have received a copy of the GNU Lesser General Public
018: * License along with this library; if not, write to the Free Software
019: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020: *
021: * Redistribution and use of this software and associated documentation ("Software"),
022: * with or without modification, are permitted provided that the following conditions are met:
023: * 1. Redistributions of source code must retain copyright statements and notices.
024: * Redistributions must also contain a copy of this document.
025: * 2. Redistributions in binary form must reproduce the above copyright notice,
026: * this list of conditions and the following disclaimer in the documentation
027: * and/or other materials provided with the distribution.
028: * 3. The name "JAFFA" must not be used to endorse or promote products derived from
029: * this Software without prior written permission. For written permission,
030: * please contact mail to: jaffagroup@yahoo.com.
031: * 4. Products derived from this Software may not be called "JAFFA" nor may "JAFFA"
032: * appear in their names without prior written permission.
033: * 5. Due credit should be given to the JAFFA Project (http://jaffa.sourceforge.net).
034: *
035: * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
036: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
037: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
038: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
039: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
040: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
041: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
042: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
043: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
044: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
045: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
046: * SUCH DAMAGE.
047: * ====================================================================
048: */
049: package org.jaffa.util;
050:
051: import org.jaffa.datatypes.DateTime;
052: import org.jaffa.util.StringHelper;
053:
054: /** To help save objects that have a technical key, this routine can voucher a
055: * unique string on length 20. It will be unique between sucessive retarts of the JVM
056: *
057: * @author paule
058: * @version 1.0
059: */
060: public class Voucher {
061:
062: private static int counter = 0;
063:
064: /** Total String Size = prefix.length(13) + digits (7) = 20chars */
065: private static int DIGITS = 7;
066: private static int COUNTER_MAX = Math.round((float) Math.pow(10,
067: DIGITS)) - 1;
068:
069: private static String prefix = null;
070:
071: private static DateTime baseDate = new DateTime();
072:
073: /** Get the next unique sequence number
074: *
075: * @return A unique string of length 20. Typically the first 13 chars represent the
076: * current date/time, and the following 7 are an index counter.
077: */
078: public static synchronized String getNext() {
079: if (counter == COUNTER_MAX) {
080: counter = 0;
081: baseDate = DateTime.addSecond(baseDate, 1);
082: prefix = null;
083: }
084:
085: return getPrefix() + StringHelper.pad(counter++, DIGITS, "0");
086: }
087:
088: /** Format of prefix is YYYYDDDHHMMSS (13 Chars)
089: * YYYY = 4 digit date, DDDD = 001-366 Day of year, HHMMSS = Hour/Minute/Seccond
090: */
091: private static String getPrefix() {
092: if (prefix == null)
093: prefix = StringHelper.pad(baseDate.getYear(), 4, "0")
094: + StringHelper.pad(baseDate.getDayOfYear(), 3, "0")
095: + StringHelper.pad(baseDate.getHourOfDay(), 2, "0")
096: + StringHelper.pad(baseDate.getMinute(), 2, "0")
097: + StringHelper.pad(baseDate.getSecond(), 2, "0");
098: return prefix;
099: }
100:
101: public static void main(String[] args) {
102:
103: for (int i = 0; i < 100; i++)
104: System.out.println("Voucher: " + Voucher.getNext());
105: }
106:
107: }
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