BasicLoader


1   //$Id: BasicLoader.java,v 1.9 2005/05/19 07:51:31 steveebersole Exp $
2   package org.hibernate.loader;
3   
4   import org.hibernate.engine.SessionFactoryImplementor;
5   import org.hibernate.persister.entity.Loadable;
6   import org.hibernate.persister.collection.CollectionPersister;
7   
8   /**
9    * Uses the default mapping from property to result set column 
10   * alias defined by the entities' persisters. Used when Hibernate
11   * is generating result set column aliases.
12   * 
13   * @author Gavin King
14   */
15  public abstract class BasicLoader extends Loader {
16  
17      protected static final String  [] NO_SUFFIX = {""};
18  
19      private EntityAliases[] descriptors;
20      private CollectionAliases[] collectionDescriptors;
21  
22      public BasicLoader(SessionFactoryImplementor factory) {
23          super(factory);
24      }
25      
26      protected final EntityAliases[] getEntityAliases() {
27          return descriptors;
28      }
29  
30      protected final CollectionAliases[] getCollectionAliases() {
31          return collectionDescriptors;
32      }
33  
34      protected abstract String  [] getSuffixes();
35      protected abstract String  [] getCollectionSuffixes();
36  
37      protected void postInstantiate() {
38          Loadable[] persisters = getEntityPersisters();
39          String  [] suffixes = getSuffixes();
40          descriptors = new EntityAliases[persisters.length];
41          for ( int i=0; i<descriptors.length; i++ ) {
42              descriptors[i] = new DefaultEntityAliases( persisters[i], suffixes[i] );
43          }
44  
45          CollectionPersister[] collectionPersisters = getCollectionPersisters();
46          if ( collectionPersisters != null ) {
47              String  [] collectionSuffixes = getCollectionSuffixes();
48              collectionDescriptors = new CollectionAliases[collectionPersisters.length];
49              for ( int i = 0; i < collectionPersisters.length; i++ ) {
50                  collectionDescriptors[i] = new GeneratedCollectionAliases( collectionPersisters[i], collectionSuffixes[i] );
51              }
52          }
53          else {
54              collectionDescriptors = null;
55          }
56      }
57      
58      /**
59       * Utility method that generates 0_, 1_ suffixes. Subclasses don't
60       * necessarily need to use this algorithm, but it is intended that
61       * they will in most cases.
62       */
63      public static String  [] generateSuffixes(int length) {
64          return generateSuffixes( 0, length );
65      }
66  
67      public static String  [] generateSuffixes(int seed, int length) {
68          if ( length == 0 ) return NO_SUFFIX;
69  
70          String  [] suffixes = new String  [length];
71          for ( int i = 0; i < length; i++ ) {
72              suffixes[i] = Integer.toString( i + seed ) + "_";
73          }
74          return suffixes;
75      }
76  
77  }
78
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