Mega Code Archive
ID generator
<![CDATA[
/*
GNU LESSER GENERAL PUBLIC LICENSE
Copyright (C) 2006 The Lobo Project
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Contact info: lobochief@users.sourceforge.net
*/
/*
* Created on Jun 7, 2005
*/
import java.util.*;
import java.util.logging.*;
import java.security.*;
import java.math.*;
import java.net.InetAddress;
/**
* @author J. H. S.
*/
public class ID {
private static final Random RANDOM1;
private static final Random RANDOM2;
private static final Random RANDOM3;
private static final long globalProcessID;
private static final Logger logger = Logger.getLogger(ID.class.getName());
static {
long time = System.currentTimeMillis();
long nanoTime = System.nanoTime();
long freeMemory = Runtime.getRuntime().freeMemory();
long addressHashCode;
try {
InetAddress inetAddress;
inetAddress = InetAddress.getLocalHost();
addressHashCode = inetAddress.getHostName().hashCode() ^ inetAddress.getHostAddress().hashCode();
} catch(Exception err) {
logger.log(Level.WARNING, "Unable to get local host information.", err);
addressHashCode = ID.class.hashCode();
}
globalProcessID = time ^ nanoTime ^ freeMemory ^ addressHashCode;
RANDOM1 = new Random(time);
RANDOM2 = new Random(nanoTime);
RANDOM3 = new Random(addressHashCode ^ freeMemory);
}
private ID() {
}
public static long generateLong() {
return Math.abs(RANDOM1.nextLong() ^ RANDOM2.nextLong() ^ RANDOM3.nextLong());
}
public static int generateInt() {
return (int) generateLong();
}
public static byte[] getMD5Bytes(String content) {
try {
MessageDigest digest = MessageDigest.getInstance("MD5");
return digest.digest(content.getBytes("UTF-8"));
} catch (NoSuchAlgorithmException e) {
throw new IllegalStateException(e);
} catch(java.io.UnsupportedEncodingException uee) {
throw new IllegalStateException(uee);
}
}
public static String getHexString(byte[] bytes) {
// This method cannot change even if it's wrong.
BigInteger bigInteger = BigInteger.ZERO;
int shift = 0;
for(int i = bytes.length; --i >= 0;) {
BigInteger contrib = BigInteger.valueOf(bytes[i] & 0xFF);
contrib = contrib.shiftLeft(shift);
bigInteger = bigInteger.add(contrib);
shift += 8;
}
return bigInteger.toString(16).toUpperCase();
}
/**
* Gets a process ID that is nearly guaranteed to be globally unique.
*/
public static long getGlobalProcessID() {
return globalProcessID;
}
public static int random(int min, int max) {
if(max <= min) {
return min;
}
return Math.abs(RANDOM1.nextInt()) % (max - min) + min;
}
}
]]>