KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > db4o > foundation > TimeStampIdGenerator


1 /* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
2
3 This file is part of the db4o open source object database.
4
5 db4o is free software; you can redistribute it and/or modify it under
6 the terms of version 2 of the GNU General Public License as published
7 by the Free Software Foundation and as clarified by db4objects' GPL
8 interpretation policy, available at
9 http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10 Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11 Suite 350, San Mateo, CA 94403, USA.
12
13 db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 package com.db4o.foundation;
22
23
24 /**
25  * @exclude
26  */
27 public class TimeStampIdGenerator {
28     
29     private long _last;
30
31     public static long idToMilliseconds(long id) {
32         return id >> 15;
33     }
34
35     public TimeStampIdGenerator() {
36         this(0);
37     }
38
39     public TimeStampIdGenerator(long minimumNext) {
40         _last = minimumNext;
41     }
42
43     public long generate() {
44         long t = System.currentTimeMillis();
45
46         t = t << 15;
47
48         if (t <= _last) {
49             _last ++;
50         } else {
51             _last = t;
52         }
53         return _last;
54     }
55
56     public long last() {
57         return _last;
58     }
59
60     public boolean setMinimumNext(long newMinimum) {
61         if(newMinimum <= _last){
62             return false;
63         }
64         _last = newMinimum;
65         return true;
66     }
67 }
68
Popular Tags