1 /** 2 * JDBM LICENSE v1.00 3 * 4 * Redistribution and use of this software and associated documentation 5 * ("Software"), with or without modification, are permitted provided 6 * that the following conditions are met: 7 * 8 * 1. Redistributions of source code must retain copyright 9 * statements and notices. Redistributions must also contain a 10 * copy of this document. 11 * 12 * 2. Redistributions in binary form must reproduce the 13 * above copyright notice, this list of conditions and the 14 * following disclaimer in the documentation and/or other 15 * materials provided with the distribution. 16 * 17 * 3. The name "JDBM" must not be used to endorse or promote 18 * products derived from this Software without prior written 19 * permission of Cees de Groot. For written permission, 20 * please contact cg@cdegroot.com. 21 * 22 * 4. Products derived from this Software may not be called "JDBM" 23 * nor may "JDBM" appear in their names without prior written 24 * permission of Cees de Groot. 25 * 26 * 5. Due credit should be given to the JDBM Project 27 * (http://jdbm.sourceforge.net/). 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS 30 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT 31 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 32 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 33 * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 34 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 35 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 36 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 38 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 39 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 40 * OF THE POSSIBILITY OF SUCH DAMAGE. 41 * 42 * Copyright 2001 (C) Alex Boisvert. All Rights Reserved. 43 * Contributions are Copyright (C) 2001 by their associated contributors. 44 * 45 */ 46 47 package jdbm.helper; 48 49 import java.io.IOException; 50 import java.io.Serializable; 51 import java.util.Comparator; 52 53 /** 54 * Comparator for objects which have been serialized into byte arrays. 55 * In effect, it wraps another Comparator which compares object and provides 56 * transparent deserialization from byte array to object. 57 * 58 * @author <a href="mailto:boisvert@intalio.com">Alex Boisvert</a> 59 * @version $Id: ObjectBAComparator.java,v 1.1 2002/05/31 06:33:20 boisvert Exp $ 60 */ 61 public final class ObjectBAComparator 62 implements Comparator, Serializable 63 { 64 65 /** 66 * Version id for serialization. 67 */ 68 final static long serialVersionUID = 1L; 69 70 71 /** 72 * Wrapped comparator. 73 */ 74 private Comparator _comparator; 75 76 77 /** 78 * Construct an ObjectByteArrayComparator which wraps an Object Comparator. 79 * 80 * @param comparator Object comparator. 81 */ 82 public ObjectBAComparator( Comparator comparator ) 83 { 84 if ( comparator == null ) { 85 throw new IllegalArgumentException( "Argument 'comparator' is null" ); 86 } 87 88 _comparator = comparator; 89 } 90 91 92 /** 93 * Compare two objects. 94 * 95 * @param obj1 First object 96 * @param obj2 Second object 97 * @return 1 if obj1 > obj2, 0 if obj1 == obj2, -1 if obj1 < obj2 98 */ 99 public int compare( Object obj1, Object obj2 ) 100 { 101 if ( obj1 == null ) { 102 throw new IllegalArgumentException( "Argument 'obj1' is null" ); 103 } 104 105 if ( obj2 == null ) { 106 throw new IllegalArgumentException( "Argument 'obj2' is null" ); 107 } 108 109 try { 110 obj1 = Serialization.deserialize( (byte[]) obj1 ); 111 obj2 = Serialization.deserialize( (byte[]) obj2 ); 112 113 return _comparator.compare( obj1, obj2 ); 114 } catch ( IOException except ) { 115 throw new WrappedRuntimeException( except ); 116 } catch ( ClassNotFoundException except ) { 117 throw new WrappedRuntimeException( except ); 118 } 119 } 120 121 122 /** 123 * Compare two byte arrays. 124 */ 125 public static int compareByteArray( byte[] thisKey, byte[] otherKey ) 126 { 127 int len = Math.min( thisKey.length, otherKey.length ); 128 129 // compare the byte arrays 130 for ( int i=0; i<len; i++ ) { 131 if ( thisKey[i] >= 0 ) { 132 if ( otherKey[i] >= 0 ) { 133 // both positive 134 if ( thisKey[i] < otherKey[i] ) { 135 return -1; 136 } else if ( thisKey[i] > otherKey[i] ) { 137 return 1; 138 } 139 } else { 140 // otherKey is negative => greater (because MSB is 1) 141 return -1; 142 } 143 } else { 144 if ( otherKey[i] >= 0 ) { 145 // thisKey is negative => greater (because MSB is 1) 146 return 1; 147 } else { 148 // both negative 149 if ( thisKey[i] < otherKey[i] ) { 150 return -1; 151 } else if ( thisKey[i] > otherKey[i] ) { 152 return 1; 153 } 154 } 155 } 156 } 157 if ( thisKey.length == otherKey.length) { 158 return 0; 159 } 160 if ( thisKey.length < otherKey.length ) { 161 return -1; 162 } 163 return 1; 164 } 165 166 }