1 /*
2 * Copyright 2006-2007 the original author or authors.
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.springframework.batch.item.file.transform;
17
18 import java.util.Collection;
19 import java.util.Map;
20
21 /**
22 * {@link FieldExtractor} that just returns the original item. If the item is an
23 * array or collection it will be returned as is, otherwise it is wrapped in a
24 * single element array.
25 *
26 * @author Dave Syer
27 *
28 */
29 public class PassThroughFieldExtractor<T> implements FieldExtractor<T> {
30
31 /**
32 * Get an array of fields as close as possible to the input. The result
33 * depends on the type of the input:
34 * <ul>
35 * <li>A {@link FieldSet} or array will be returned as is</li>
36 * <li>For a Collection the <code>toArray()</code> method will be used</li>
37 * <li>For a Map the <code>values()</code> will be returned as an array</li>
38 * <li>Otherwise it is wrapped in a single element array.</li>
39 * </ul>
40 * Note that no attempt is made to sort the values, so passing in an
41 * unordered collection or map is probably a bad idea. Spring often gives
42 * you an ordered Map (e.g. if extracting data from a generic query using
43 * JDBC), so check the documentation for whatever is being used to generate
44 * the input.
45 *
46 * @param item the object to convert
47 * @return an array of objects as close as possible to the original item
48 */
49 @Override
50 public Object[] extract(T item) {
51
52 if (item.getClass().isArray()) {
53 return (Object[]) item;
54 }
55
56 if (item instanceof Collection<?>) {
57 return ((Collection<?>) item).toArray();
58 }
59
60 if (item instanceof Map<?, ?>) {
61 return ((Map<?, ?>) item).values().toArray();
62 }
63
64 if (item instanceof FieldSet) {
65 return ((FieldSet) item).getValues();
66 }
67
68 return new Object[] { item };
69
70 }
71
72 }