1 /* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
2 *
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 package org.acegisecurity.acl.basic;
17
18 import java.io.Serializable;
19
20
21 /**
22 * Interface representing the identity of an individual domain object instance.
23 *
24 * <P>
25 * It should be noted that <code>AclObjectIdentity</code> instances are created
26 * in various locations throughout the package. As
27 * <code>AclObjectIdentity</code>s are used as the key for caching, it is
28 * essential that implementations provide methods so that object-equality
29 * rather than reference-equality can be relied upon by caches. In other
30 * words, a cache can consider two <code>AclObjectIdentity</code>s equal if
31 * <code>identity1.equals(identity2)</code>, rather than reference-equality of
32 * <code>identity1==identity2</code>.
33 * </p>
34 *
35 * <P>
36 * In practical terms this means you must implement the standard
37 * <code>java.lang.Object</code> methods shown below. Depending on your
38 * cache's internal structure, you may also need to implement special
39 * interfaces such as <code>java.util.Comparator</code> or
40 * <code>java.lang.Comparable</code>.
41 * </p>
42 *
43 * @author Ben Alex
44 * @version $Id: AclObjectIdentity.java 1784 2007-02-24 21:00:24Z luke_t $
45 */
46 public interface AclObjectIdentity extends Serializable {
47 //~ Methods ========================================================================================================
48
49 /**
50 * Refer to the <code>java.lang.Object</code> documentation for the interface contract.
51 *
52 * @param obj to be compared
53 *
54 * @return <code>true</code> if the objects are equal, <code>false</code> otherwise
55 */
56 boolean equals(Object obj);
57
58 /**
59 * Refer to the <code>java.lang.Object</code> documentation for the interface contract.
60 *
61 * @return a hash code representation of this object
62 */
63 int hashCode();
64 }