guidgenerator.java

一个免费的CA,基于EJB平台的,老师叫我们测试,现把之共享出来让大家参考

/*************************************************************************
 *                                                                       *
 *  EJBCA: The OpenSource Certificate Authority                          *
 *                                                                       *
 *  This software 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 any later version.                    *
 *                                                                       *
 *  See terms of license at gnu.org.                                     *
 *                                                                       *
 *************************************************************************/

package org.ejbca.util;

import org.apache.log4j.Logger;

/** Shamelessly ripped from generated XDoclet source, because I don't want to generate util classes.
 * 
 * @author XDoclet.sf.net
 * @version $Id: GUIDGenerator.java,v 1.1 2006/08/05 09:59:37 anatom Exp $
 */
public class GUIDGenerator {
	private static final Logger log = Logger.getLogger(GUIDGenerator.class);

	   /** Cached per JVM server IP. */
	   private static String hexServerIP = null;

	   // initialise the secure random instance
	   private static final java.security.SecureRandom seeder = new java.security.SecureRandom();
	   
	   /**
	    * A 32 byte GUID generator (Globally Unique ID). These artificial keys SHOULD <strong>NOT </strong> be seen by the user,
	    * not even touched by the DBA but with very rare exceptions, just manipulated by the database and the programs.
	    *
	    * Usage: Add an id field (type java.lang.String) to your EJB, and add setId(XXXUtil.generateGUID(this)); to the ejbCreate method.
	    */
	   public static final String generateGUID(Object o) {
	       StringBuffer tmpBuffer = new StringBuffer(16);
	       if (hexServerIP == null) {
	           java.net.InetAddress localInetAddress = null;
	           try {
	               // get the inet address
	               localInetAddress = java.net.InetAddress.getLocalHost();
	           }
	           catch (java.net.UnknownHostException uhe) {
	               log.error("Could not get the local IP address using InetAddress.getLocalHost(): ", uhe);
	               // todo: find better way to get around this...
	               return null;
	           }
	           byte serverIP[] = localInetAddress.getAddress();
	           hexServerIP = hexFormat(getInt(serverIP), 8);
	       }

	       String hashcode = hexFormat(System.identityHashCode(o), 8);
	       tmpBuffer.append(hexServerIP);
	       tmpBuffer.append(hashcode);

	       long timeNow      = System.currentTimeMillis();
	       int timeLow       = (int)timeNow & 0xFFFFFFFF;
	       int node          = seeder.nextInt();

	       StringBuffer guid = new StringBuffer(32);
	       guid.append(hexFormat(timeLow, 8));
	       guid.append(tmpBuffer.toString());
	       guid.append(hexFormat(node, 8));
	       return guid.toString();
	   }
	   
	   private static int getInt(byte bytes[]) {
	       int i = 0;
	       int j = 24;
	       for (int k = 0; j >= 0; k++) {
	           int l = bytes[k] & 0xff;
	           i += l << j;
	           j -= 8;
	       }
	       return i;
	   }

	   private static String hexFormat(int i, int j) {
	       String s = Integer.toHexString(i);
	       return padHex(s, j) + s;
	   }

	   private static String padHex(String s, int i) {
	       StringBuffer tmpBuffer = new StringBuffer();
	       if (s.length() < i) {
	           for (int j = 0; j < i - s.length(); j++) {
	               tmpBuffer.append('0');
	           }
	       }
	       return tmpBuffer.toString();
	   }
}