1 /*
2 * Hibernate, Relational Persistence for Idiomatic Java
3 *
4 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
5 * indicated by the @author tags or express copyright attribution
6 * statements applied by the authors. All third-party contributions are
7 * distributed under license by Red Hat Middleware LLC.
8 *
9 * This copyrighted material is made available to anyone wishing to use, modify,
10 * copy, or redistribute it subject to the terms and conditions of the GNU
11 * Lesser General Public License, as published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
16 * for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public License
19 * along with this distribution; if not, write to:
20 * Free Software Foundation, Inc.
21 * 51 Franklin Street, Fifth Floor
22 * Boston, MA 02110-1301 USA
23 *
24 */
25 package org.hibernate.loader;
26
27 import org.hibernate.engine.SessionFactoryImplementor;
28 import org.hibernate.persister.entity.Loadable;
29 import org.hibernate.persister.collection.CollectionPersister;
30 import org.hibernate.type.BagType;
31 import org.hibernate.HibernateException;
32
33 /**
34 * Uses the default mapping from property to result set column
35 * alias defined by the entities' persisters. Used when Hibernate
36 * is generating result set column aliases.
37 *
38 * @author Gavin King
39 */
40 public abstract class BasicLoader extends Loader {
41
42 protected static final String[] NO_SUFFIX = {""};
43
44 private EntityAliases[] descriptors;
45 private CollectionAliases[] collectionDescriptors;
46
47 public BasicLoader(SessionFactoryImplementor factory) {
48 super(factory);
49 }
50
51 protected final EntityAliases[] getEntityAliases() {
52 return descriptors;
53 }
54
55 protected final CollectionAliases[] getCollectionAliases() {
56 return collectionDescriptors;
57 }
58
59 protected abstract String[] getSuffixes();
60 protected abstract String[] getCollectionSuffixes();
61
62 protected void postInstantiate() {
63 Loadable[] persisters = getEntityPersisters();
64 String[] suffixes = getSuffixes();
65 descriptors = new EntityAliases[persisters.length];
66 for ( int i=0; i<descriptors.length; i++ ) {
67 descriptors[i] = new DefaultEntityAliases( persisters[i], suffixes[i] );
68 }
69
70 CollectionPersister[] collectionPersisters = getCollectionPersisters();
71 int bagCount = 0;
72 if ( collectionPersisters != null ) {
73 String[] collectionSuffixes = getCollectionSuffixes();
74 collectionDescriptors = new CollectionAliases[collectionPersisters.length];
75 for ( int i = 0; i < collectionPersisters.length; i++ ) {
76 if ( isBag( collectionPersisters[i] ) ) {
77 bagCount++;
78 }
79 collectionDescriptors[i] = new GeneratedCollectionAliases(
80 collectionPersisters[i],
81 collectionSuffixes[i]
82 );
83 }
84 }
85 else {
86 collectionDescriptors = null;
87 }
88 if ( bagCount > 1 ) {
89 throw new HibernateException( "cannot simultaneously fetch multiple bags" );
90 }
91 }
92
93 private boolean isBag(CollectionPersister collectionPersister) {
94 return collectionPersister.getCollectionType().getClass().isAssignableFrom( BagType.class );
95 }
96
97 /**
98 * Utility method that generates 0_, 1_ suffixes. Subclasses don't
99 * necessarily need to use this algorithm, but it is intended that
100 * they will in most cases.
101 */
102 public static String[] generateSuffixes(int length) {
103 return generateSuffixes( 0, length );
104 }
105
106 public static String[] generateSuffixes(int seed, int length) {
107 if ( length == 0 ) return NO_SUFFIX;
108
109 String[] suffixes = new String[length];
110 for ( int i = 0; i < length; i++ ) {
111 suffixes[i] = Integer.toString( i + seed ) + "_";
112 }
113 return suffixes;
114 }
115
116 }
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