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Java > Open Source Codes > org > apache > ojb > broker > query > QueryByIdentity


1 package org.apache.ojb.broker.query;
2
3 /* Copyright 2002-2005 The Apache Software Foundation
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 import org.apache.ojb.broker.Identity;
19
20 /**
21  * Represents a search by identity.
22  * <i>"find the article with id 7"</i>
23  * could be represented as:<br/>
24  * <br/>
25  *
26  * <code>
27  * Article example = new Article();<br/>
28  * example.setId(7);<br/>
29  * Query qry = new QueryByIdentity(example);<br/>
30  * </code>
31  * <br/>
32  * The PersistenceBroker can retrieve Objects by examples as follows:<br/>
33  * <br/>
34  * <code>
35  * PersistenceBroker broker = PersistenceBrokerFactory.createPersistenceBroker();<br/>
36  * Collection col = broker.getObjectByQuery(qry);<br/>
37  * </code>
38  * <br/>
39  * This Class can also handle working with OJB Identity objects:
40  * <i>"find the article with Identity xyz"</i> could be represnted as<br/>
41  * <br/>
42  * <code>
43  * Article example = new Article();<br/>
44  * example.setId(7);<br/>
45  * Identity xyz = broker.serviceIdentity().buildIdentity(example);<br/>
46  * Query qry = new QueryByIdentity(xyz);<br/>
47  * Collection col = broker.getObjectByQuery(qry);<br/>
48  * </code>
49  * <br/>
50  * But in this case a smarter solution will be<br/>
51  * <br/>
52  * <code>
53  * Identity xyz = broker.serviceIdentity().buildIdentity(Article.class, new Integer(7));<br/>
54  * Collection col = broker.getObjectByIdentity(xyz);<br/>
55  * </code>
56  *
57  * @author <a HREF="mailto:thma@apache.org">Thomas Mahler<a>
58  * @version $Id: QueryByIdentity.java,v 1.9.2.3 2005/12/21 22:27:09 tomdz Exp $
59  */
60 public class QueryByIdentity extends AbstractQueryImpl
61 {
62     private Object JavaDoc m_exampleObjectOrIdentity;
63
64     /**
65      * QueryByIdentity can be generated from example Objects or by Identity Objects
66      */
67     public QueryByIdentity(Object JavaDoc example_or_identity)
68     {
69         m_exampleObjectOrIdentity = example_or_identity;
70     }
71
72     /**
73      * Answer the example Object
74      * @return the example Object or an Identity
75      */
76     public Object JavaDoc getExampleObject()
77     {
78         return m_exampleObjectOrIdentity;
79     }
80
81     /**
82      * Answer the search class.
83      * This is the class of the example object or
84      * the class represented by Identity.
85      * @return Class
86      */
87     public Class JavaDoc getSearchClass()
88     {
89         Object JavaDoc obj = getExampleObject();
90
91         if (obj instanceof Identity)
92         {
93             return ((Identity) obj).getObjectsTopLevelClass();
94         }
95         else
96         {
97             return obj.getClass();
98         }
99     }
100
101 }
102
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