1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. 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 package org.apache.commons.betwixt.io.read;
18
19 import java.util.ArrayList;
20 import java.util.Iterator;
21
22 /**
23 * <p>Chain implementation that's backed by a list.
24 * This is the default implementation used by Betwixt.
25 * </p><p>
26 * <strong>Note</strong> this implementation is <em>not</em>
27 * intended to allow multiple threads of execution to perform
28 * modification operations concurrently with traversal of the chain.
29 * Users who require this behaviour are advised to create their own implementation.
30 * </p>
31 *
32 * @author Robert Burrell Donkin
33 * @since 0.5
34 */
35 public class BeanCreationList extends BeanCreationChain {
36
37 //-------------------------------------------------------- Class Methods
38
39 /**
40 * Creates the default <code>BeanCreationChain</code> used when reading beans.
41 * @return a <code>BeanCreationList</code> with the default creators loader in order, not null
42 */
43 public static final BeanCreationList createStandardChain() {
44 BeanCreationList chain = new BeanCreationList();
45 chain.addBeanCreator( ChainedBeanCreatorFactory.createIDREFBeanCreator() );
46 chain.addBeanCreator( ChainedBeanCreatorFactory.createDerivedBeanCreator() );
47 chain.addBeanCreator( ChainedBeanCreatorFactory.createElementTypeBeanCreator() );
48 return chain;
49 }
50
51
52
53 //-------------------------------------------------------- Attributes
54 /** The list backing this chain */
55 private ArrayList beanCreators = new ArrayList();
56
57 //-------------------------------------------------------- Methods
58
59 /**
60 * Creates an Object based on the given element mapping and read context.
61 * Delegates to chain.
62 *
63 * @param elementMapping the element mapping details
64 * @param readContext create against this context
65 * @return the created bean, possibly null
66 */
67 public Object create( ElementMapping elementMapping, ReadContext readContext ) {
68 ChainWorker worker = new ChainWorker();
69 return worker.create( elementMapping, readContext );
70 }
71
72 //-------------------------------------------------------- Properties
73
74 /**
75 * Gets the number of BeanCreators in the wrapped chain.
76 * @return the number of <code>ChainedBeanCreator</code>'s in the current chain
77 */
78 public int getSize() {
79 return beanCreators.size();
80 }
81
82 /**
83 * Inserts a <code>BeanCreator</code> at the given position in the chain.
84 * Shifts the object currently in that position - and any subsequent elements -
85 * to the right.
86 *
87 * @param index index at which the creator should be inserted
88 * @param beanCreator the <code>BeanCreator</code> to be inserted, not null
89 * @throws IndexOutOfBoundsException if the index is out of the range
90 * <code>(index < 0 || index > getSize())
91 */
92 public void insertBeanCreator(
93 int index,
94 ChainedBeanCreator beanCreator )
95 throws IndexOutOfBoundsException {
96 beanCreators.add( index, beanCreator );
97 }
98
99 /**
100 * Adds a <code>BeanCreator</code> to the end of the chain.
101 * @param beanCreator the <code>BeanCreator</code> to be inserted, not null
102 */
103 public void addBeanCreator( ChainedBeanCreator beanCreator ) {
104 beanCreators.add( beanCreator );
105 }
106
107 /**
108 * Clears the creator chain.
109 */
110 public void clearBeanCreators() {
111 beanCreators.clear();
112 }
113
114 /** Worker class walks a chain */
115 private class ChainWorker extends BeanCreationChain {
116 /** Iterator for the creator list */
117 private Iterator iterator;
118 /** Creates the iterator */
119 ChainWorker() {
120 iterator = beanCreators.iterator();
121 }
122
123 /**
124 * @see BeanCreationChain#create
125 */
126 public Object create( ElementMapping elementMapping, ReadContext readContext ) {
127 if ( iterator.hasNext() ) {
128 ChainedBeanCreator beanCreator = (ChainedBeanCreator) iterator.next();
129 return beanCreator.create( elementMapping, readContext, this );
130 }
131
132 return null;
133 }
134 }
135 }