1 /********************************************************************************
2 *InternetCafe is a software solution that helps the management of Cybercafes
3 * according with the ITALIAN DECREE LAW ON ANTI-TERROR MEASURES, 27 JULY 2005.
4 * Copyright (C) 2006 Guido Angelo Ingenito
5
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
10
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
19 *******************************************************************************/
20 package base.jdbs;
21
22 import java.math.BigInteger;
23 import java.security.SecureRandom;
24
25 import org.apache.log4j.Logger;
26
27 public class GUIDGenerator {
28
29 private static final transient Logger logger = Logger.getLogger(GUIDGenerator.class.getName());
30
31 /***The secure random to use when must be build a global unique identifier.**/
32 private SecureRandom secureRandom;
33 /***The GUIDGenerator instance according to the Singleton pattern.**/
34 private static GUIDGenerator instance = null;
35
36
37 /***
38 * @return Returns the instance.
39 */
40 public static GUIDGenerator getInstance(){
41 return instance!=null ? instance : (instance = new GUIDGenerator());
42 }
43
44 /***
45 * The default constructor.
46 */
47 protected GUIDGenerator(){
48 this.secureRandom = new SecureRandom();
49 logger.debug(secureRandom.getProvider().getInfo());
50 }
51
52 /***
53 * This method returns a alphanumeric key that is unique to a millisecond. The uniqueness
54 * is increased by appending a random number to the key.
55 * @return The unique key.
56 */
57 public String getAlphanumericKey() {
58
59
60 String key = "" + System.currentTimeMillis() + Long.toHexString(secureRandom.nextInt());
61 logger.debug("getAlphanumericKey(): "+key);
62 return key;
63 }
64
65 /***
66 * This method returns a numeric key that is unique to a millisecond. The uniqueness
67 * is increased by appending a random number to the key.
68 * @return The unique key.
69 */
70 public BigInteger getNumericKey() {
71
72
73 String firstToken = ""+System.currentTimeMillis();
74 Long secureToken = secureRandom.nextLong();
75 String lastToken = secureToken > 0 ? ""+secureToken : ""+(-1 * secureToken);
76 BigInteger key = new BigInteger(firstToken+lastToken);
77 logger.debug("getNumericKey(): "+key);
78 return key;
79 }
80
81 }