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Java > Open Source Codes > org > apache > commons > betwixt > io > read > BeanCreationList


1 /*
2  * Copyright 2001-2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.betwixt.io.read;
17
18 import java.util.ArrayList JavaDoc;
19 import java.util.Iterator JavaDoc;
20
21 /**
22   * <p>Chain implementation that's backed by a list.
23   * This is the default implementation used by Betwixt.
24   * </p><p>
25   * <strong>Note</strong> this implementation is <em>not</em>
26   * intended to allow multiple threads of execution to perform
27   * modification operations concurrently with traversal of the chain.
28   * Users who require this behaviour are advised to create their own implementation.
29   * </p>
30   *
31   * @author Robert Burrell Donkin
32   * @since 0.5
33   */
34 public class BeanCreationList extends BeanCreationChain {
35     
36 //-------------------------------------------------------- Class Methods
37
38     /**
39      * Creates the default <code>BeanCreationChain</code> used when reading beans.
40      * @return a <code>BeanCreationList</code> with the default creators loader in order, not null
41      */
42     public static final BeanCreationList createStandardChain() {
43         BeanCreationList chain = new BeanCreationList();
44         chain.addBeanCreator( ChainedBeanCreatorFactory.createIDREFBeanCreator() );
45         chain.addBeanCreator( ChainedBeanCreatorFactory.createDerivedBeanCreator() );
46         chain.addBeanCreator( ChainedBeanCreatorFactory.createElementTypeBeanCreator() );
47         return chain;
48     }
49     
50
51     
52 //-------------------------------------------------------- Attributes
53 /** The list backing this chain */
54     private ArrayList JavaDoc beanCreators = new ArrayList JavaDoc();
55     
56 //-------------------------------------------------------- Methods
57
58     /**
59       * Creates an Object based on the given element mapping and read context.
60       * Delegates to chain.
61       *
62       * @param elementMapping the element mapping details
63       * @param readContext create against this context
64       * @return the created bean, possibly null
65       */
66     public Object JavaDoc create( ElementMapping elementMapping, ReadContext readContext ) {
67         ChainWorker worker = new ChainWorker();
68         return worker.create( elementMapping, readContext );
69     }
70     
71 //-------------------------------------------------------- Properties
72
73     /**
74       * Gets the number of BeanCreators in the wrapped chain.
75       * @return the number of <code>ChainedBeanCreator</code>'s in the current chain
76       */
77     public int getSize() {
78         return beanCreators.size();
79     }
80     
81     /**
82       * Inserts a <code>BeanCreator</code> at the given position in the chain.
83       * Shifts the object currently in that position - and any subsequent elements -
84       * to the right.
85       *
86       * @param index index at which the creator should be inserted
87       * @param beanCreator the <code>BeanCreator</code> to be inserted, not null
88       * @throws IndexOutOfBoundsException if the index is out of the range
89       * <code>(index < 0 || index > getSize())
90       */
91     public void insertBeanCreator(
92                                 int index,
93                                 ChainedBeanCreator beanCreator )
94                                     throws IndexOutOfBoundsException JavaDoc {
95         beanCreators.add( index, beanCreator );
96     }
97     
98     /**
99       * Adds a <code>BeanCreator</code> to the end of the chain.
100       * @param beanCreator the <code>BeanCreator</code> to be inserted, not null
101       */
102     public void addBeanCreator( ChainedBeanCreator beanCreator ) {
103         beanCreators.add( beanCreator );
104     }
105     
106     /**
107       * Clears the creator chain.
108       */
109     public void clearBeanCreators() {
110         beanCreators.clear();
111     }
112      
113     /** Worker class walks a chain */
114     private class ChainWorker extends BeanCreationChain {
115         /** Iterator for the creator list */
116         private Iterator JavaDoc iterator;
117         /** Creates the iterator */
118         ChainWorker() {
119             iterator = beanCreators.iterator();
120         }
121     
122         /**
123           * @see BeanCreationChain#create
124           */
125         public Object JavaDoc create( ElementMapping elementMapping, ReadContext readContext ) {
126             if ( iterator.hasNext() ) {
127                 ChainedBeanCreator beanCreator = (ChainedBeanCreator) iterator.next();
128                 return beanCreator.create( elementMapping, readContext, this );
129             }
130             
131             return null;
132         }
133     }
134 }
135
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