UUID generator from Sun Microsystems
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can obtain
* a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
* or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
* Sun designates this particular file as subject to the "Classpath" exception
* as provided by Sun in the GPL Version 2 section of the License file that
* accompanied this code. If applicable, add the following below the License
* Header, with the fields enclosed by brackets [] replaced by your own
* identifying information: "Portions Copyrighted [year]
* [name of copyright owner]"
*
* Contributor(s):
*
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
/*
* UuidUtil.java
*
* Created on October 15, 2002, 9:39 AM
*/
import java.net.InetAddress;
import java.rmi.server.UID;
import java.security.SecureRandom;
/**
* Class UuidUtil
*
*
*/
public class UuidUtil {
static final String _inetAddr = initInetAddr();
// first method (from MarketMaker Guid)
public static String generateUuidMM() {
return new StringBuffer(new UID().toString()).reverse().append(':').append(_inetAddr)
.toString();
}
// second method
public static String generateUuid() {
return generateUuid(new Object());
}
// this method can take in the session object
// and insure better uniqueness guarantees
public static String generateUuid(Object obj) {
// low order time bits
long presentTime = System.currentTimeMillis();
int presentTimeLow = (int) presentTime & 0xFFFFFFFF;
String presentTimeStringLow = formatHexString(presentTimeLow);
StringBuffer sb = new StringBuffer(50);
sb.append(presentTimeStringLow);
// sb.append(":");
sb.append(getIdentityHashCode(obj));
// sb.append(":");
// sb.append(_inetAddr);
sb.append(addRandomTo(_inetAddr));
// sb.append(":");
sb.append(getNextRandomString());
return sb.toString();
}
/**
* Method initInetAddr
*
*
* @return
*
* @audience
*/
private static String initInetAddr() {
try {
byte[] bytes = InetAddress.getLocalHost().getAddress();
StringBuffer b = new StringBuffer();
String s = null;
for (int i = 0; i < bytes.length; i++) {
s = Integer.toHexString(bytes[i]);
if (bytes[i] < 0) {
b.append(s.substring(s.length() - 2));
} else {
b.append(s);
}
}
return b.toString();
} catch (Exception ex) {
// must return a value
return "a48eb993";
// return null;
}
}
private static String addRandomTo(String hexString) {
long hexAsLong = convertToLong(hexString);
int nextRandom = getNextInt();
long resultInt = hexAsLong + nextRandom;
String result = Long.toHexString(resultInt);
// START PWC 6425338
// Always return a length of 7
int len = result.length();
if (len < 7) {
result = padto7(result);
} else {
result = result.substring(len - 7, len);
}
// END PWC 6425338
return result;
}
/**
* Method getIdentityHashCode
*
*
* @return
*
* @audience
*/
private static String getIdentityHashCode(Object obj) {
String result = null;
try {
int hc = System.identityHashCode(obj);
return formatHexString(hc);
} catch (Exception ex) {
// must return a value
// return null;
return "8AF5182";
}
}
private static String formatHexString(int inputInt) {
String result = null;
String s = Integer.toHexString(inputInt);
/*
* PWC 6425338 if(s.length() < 8) { result = s; } else { result =
* s.substring(0, 7); }
*/
// START PWC 6425338
// Always return a length of 7
int len = s.length();
if (len < 7) {
result = padto7(s);
} else {
result = s.substring(len - 7, len);
}
// END PWC 6425338
return result;
}
private static synchronized int getNextInt() {
return _seeder.nextInt();
}
private static String getNextRandomString() {
int nextInt = getNextInt();
return formatHexString(nextInt);
}
private static long convertToLong(String hexString) {
long result = 0;
try {
result = (Long.valueOf(hexString, 16)).longValue();
} catch (NumberFormatException ex) {
}
return result;
}
private static SecureRandom _seeder = new SecureRandom();
/**
* Method main
*
*
* @param args
*
* @audience
*/
public static void main(String[] args) {
System.out.println(UuidUtil.generateUuidMM());
System.out.println(UuidUtil.generateUuid());
System.out.println(UuidUtil.generateUuid(new Object()));
}
// START PWC 6425338
/*
* Pads the given string to a length of 7.
*/
private static String padto7(String s) {
int i = 0;
char[] chars = new char[7];
int len = s.length();
while (i < len) {
chars[i] = s.charAt(i);
i++;
}
while (i < 7) {
chars[i++] = '0';
}
return new String(chars);
}
// END PWC 6425338
}
Related examples in the same category