| 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 | } |