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Java > Open Source Codes > org > objectstyle > cayenne > dataview > LookupCache


1 /* ====================================================================
2 *
3 * The ObjectStyle Group Software License, version 1.1
4 * ObjectStyle Group - http://objectstyle.org/
5 *
6 * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7 * of the software. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution, if any,
22 * must include the following acknowlegement:
23 * "This product includes software developed by independent contributors
24 * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25 * Alternately, this acknowlegement may appear in the software itself,
26 * if and wherever such third-party acknowlegements normally appear.
27 *
28 * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
29 * or promote products derived from this software without prior written
30 * permission. For written permission, email
31 * "andrus at objectstyle dot org".
32 *
33 * 5. Products derived from this software may not be called "ObjectStyle"
34 * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
35 * names without prior written permission.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals and hosted on ObjectStyle Group web site. For more
53 * information on the ObjectStyle Group, please see
54 * <http://objectstyle.org/>.
55 */

56 package org.objectstyle.cayenne.dataview;
57
58 import java.util.HashMap JavaDoc;
59 import java.util.Iterator JavaDoc;
60 import java.util.List JavaDoc;
61 import java.util.Map JavaDoc;
62
63 import org.objectstyle.cayenne.DataObject;
64
65 /**
66  * @since 1.1
67  * @author Andriy Shapochka
68  */

69 public class LookupCache {
70
71     private Map JavaDoc fieldCache = new HashMap JavaDoc();
72     private static final Object JavaDoc[] EMPTY_ARRAY = new Object JavaDoc[] {};
73
74     public LookupCache() {
75     }
76
77     public void cache(ObjEntityViewField field, List JavaDoc dataObjects) {
78         Lookup lookup = getLookup(field);
79         if (lookup == null) {
80             lookup = new Lookup();
81             fieldCache.put(field, lookup);
82         }
83         lookup.cache(field, dataObjects);
84     }
85
86     public void clear() {
87         fieldCache.clear();
88     }
89
90     public boolean removeFromCache(ObjEntityViewField field) {
91         return fieldCache.remove(field) != null;
92     }
93
94     public Object JavaDoc[] getCachedValues(ObjEntityViewField field) {
95         Lookup lookup = getLookup(field);
96         Object JavaDoc[] values = (lookup != null ? lookup.values : EMPTY_ARRAY);
97         if (values.length == 0)
98             return values;
99         else {
100             Object JavaDoc[] valuesCopy = new Object JavaDoc[values.length];
101             System.arraycopy(values, 0, valuesCopy, 0, values.length);
102             return valuesCopy;
103         }
104     }
105
106     public DataObject getDataObject(ObjEntityViewField field, Object JavaDoc value) {
107         Lookup lookup = getLookup(field);
108         if (lookup == null)
109             return null;
110         return lookup.getDataObject(value);
111     }
112
113     private Lookup getLookup(ObjEntityViewField field) {
114         if (field == null)
115             return null;
116         return (Lookup) fieldCache.get(field);
117     }
118
119     private class Lookup {
120
121         ObjEntityViewField field;
122         Object JavaDoc[] values = EMPTY_ARRAY;
123         Map JavaDoc valueDataObjectMap;
124
125         void cache(ObjEntityViewField field, List JavaDoc dataObjects) {
126             this.field = field;
127             if (values.length != dataObjects.size())
128                 values = new Object JavaDoc[dataObjects.size()];
129             valueDataObjectMap = new HashMap JavaDoc(values.length + 1);
130             int index = 0;
131             for (Iterator JavaDoc i = dataObjects.iterator(); i.hasNext();) {
132                 DataObject item = (DataObject) i.next();
133                 values[index] = field.getValue(item);
134                 valueDataObjectMap.put(values[index], item);
135                 index++;
136             }
137         }
138
139         DataObject getDataObject(Object JavaDoc value) {
140             return (DataObject) valueDataObjectMap.get(value);
141         }
142     }
143 }
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