001/*
002 * Copyright 2005-2008 The Kuali Foundation
003 * 
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 * 
008 * http://www.opensource.org/licenses/ecl2.php
009 * 
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.kns.util;
017
018import java.security.MessageDigest;
019import java.security.NoSuchAlgorithmException;
020
021import org.apache.ojb.broker.util.GUID;
022
023/**
024 * 
025 * This class wraps an OJB Guid so that it conforms to the format (and using the algorithm) described in
026 * RFC 4122 entitled " A Universally Unique IDentifier (UUID) URN Namespace" 
027 */
028public class Guid {
029 
030    private final static char HYPHEN='-';
031    private final static String DIGITS="0123456789ABCDEF";
032    private String stringValue=null;
033    private GUID guid;
034    
035    public Guid() {
036        
037        guid = new GUID(); // This OJB class is deprecated; remove this line when we upgrade OJB
038        
039        
040        String guidString=guid.toString();
041        // this is roughly the prefered way with the new OJB GUIDFactory:
042        // String guidString=org.apache.ojb.broker.util.GUIDFactory.next(); 
043        
044    
045        MessageDigest sha;
046        try {
047            sha = MessageDigest.getInstance("SHA-1");
048        }
049        catch (NoSuchAlgorithmException e) {
050            throw new RuntimeException(e);
051        }
052        sha.update(guidString.getBytes());
053        byte[] hash=sha.digest();
054        
055        StringBuffer result=new StringBuffer();
056        for (int i=0; i<hash.length; i++) {
057            result.append(toHex(hash[i]));
058        }
059        
060        // hyphenate
061        for (int i=20; i>4; i-=4) {
062            result.insert(i,HYPHEN);
063        }
064        
065        // truncate
066        result.delete(32,40);
067        stringValue=result.toString();
068    }    
069    
070    public static String toHex(byte b) {
071
072        int ub=b<0?b+256:b;
073        
074        StringBuffer result=new StringBuffer(2);
075        result.append(DIGITS.charAt(ub/16));
076        result.append(DIGITS.charAt(ub%16));
077        
078        return result.toString();
079    }
080
081    @Override
082    public String toString() {
083        return stringValue;
084    }
085    
086}