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Java > Open Source Codes > org > lobobrowser > util > ID


1 /*
2     GNU LESSER GENERAL PUBLIC LICENSE
3     Copyright (C) 2006 The Lobo Project
4
5     This library is free software; you can redistribute it and/or
6     modify it under the terms of the GNU Lesser General Public
7     License as published by the Free Software Foundation; either
8     version 2.1 of the License, or (at your option) any later version.
9
10     This library is distributed in the hope that it will be useful,
11     but WITHOUT ANY WARRANTY; without even the implied warranty of
12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13     Lesser General Public License for more details.
14
15     You should have received a copy of the GNU Lesser General Public
16     License along with this library; if not, write to the Free Software
17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
19     Contact info: xamjadmin@users.sourceforge.net
20 */
21 /*
22  * Created on Jun 7, 2005
23  */
24 package org.lobobrowser.util;
25
26 import java.util.*;
27 import java.util.logging.*;
28 import java.security.*;
29 import java.math.*;
30 import java.net.InetAddress JavaDoc;
31
32 /**
33  * @author J. H. S.
34  */
35 public class ID {
36     private static final Random RANDOM1;
37     private static final Random RANDOM2;
38     private static final Random RANDOM3;
39     private static final long globalProcessID;
40     private static final Logger logger = Logger.getLogger(ID.class.getName());
41
42     static {
43         long time = System.currentTimeMillis();
44         long nanoTime = System.nanoTime();
45         long freeMemory = Runtime.getRuntime().freeMemory();
46         long addressHashCode;
47         try {
48             InetAddress JavaDoc inetAddress;
49             inetAddress = InetAddress.getLocalHost();
50             addressHashCode = inetAddress.getHostName().hashCode() ^ inetAddress.getHostAddress().hashCode();
51         } catch(Exception JavaDoc err) {
52             logger.log(Level.WARNING, "Unable to get local host information.", err);
53             addressHashCode = ID.class.hashCode();
54         }
55         globalProcessID = time ^ nanoTime ^ freeMemory ^ addressHashCode;
56         RANDOM1 = new Random(time);
57         RANDOM2 = new Random(nanoTime);
58         RANDOM3 = new Random(addressHashCode ^ freeMemory);
59     }
60     
61     private ID() {
62     }
63     
64     public static long generateLong() {
65         return Math.abs(RANDOM1.nextLong() ^ RANDOM2.nextLong() ^ RANDOM3.nextLong());
66     }
67     
68     public static int generateInt() {
69         return (int) generateLong();
70     }
71     
72     public static byte[] getMD5Bytes(String JavaDoc content) {
73         try {
74             MessageDigest digest = MessageDigest.getInstance("MD5");
75             return digest.digest(content.getBytes("UTF-8"));
76         } catch (NoSuchAlgorithmException e) {
77             throw new IllegalStateException JavaDoc(e);
78         } catch(java.io.UnsupportedEncodingException JavaDoc uee) {
79             throw new IllegalStateException JavaDoc(uee);
80         }
81     }
82
83     public static String JavaDoc getHexString(byte[] bytes) {
84         // This method cannot change even if it's wrong.
85 BigInteger bigInteger = BigInteger.ZERO;
86         int shift = 0;
87         for(int i = bytes.length; --i >= 0;) {
88             BigInteger contrib = BigInteger.valueOf(bytes[i] & 0xFF);
89             contrib = contrib.shiftLeft(shift);
90             bigInteger = bigInteger.add(contrib);
91             shift += 8;
92         }
93         return bigInteger.toString(16).toUpperCase();
94     }
95     
96     /**
97      * Gets a process ID that is nearly guaranteed to be globally unique.
98      */
99     public static long getGlobalProcessID() {
100         return globalProcessID;
101     }
102     
103     public static int random(int min, int max) {
104         if(max <= min) {
105             return min;
106         }
107         return Math.abs(RANDOM1.nextInt()) % (max - min) + min;
108     }
109 }
110
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