| 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 | |
| 17 | package org.springframework.batch.item.file.transform; |
| 18 | |
| 19 | import java.util.Collection; |
| 20 | |
| 21 | |
| 22 | /** |
| 23 | * An implementation of {@link LineAggregator} that concatenates a collection of |
| 24 | * items of a common type with the system line separator. |
| 25 | * |
| 26 | * @author Dave Syer |
| 27 | * |
| 28 | */ |
| 29 | public class RecursiveCollectionLineAggregator<T> implements LineAggregator<Collection<T>> { |
| 30 | |
| 31 | private static final String LINE_SEPARATOR = System.getProperty("line.separator"); |
| 32 | |
| 33 | private LineAggregator<T> delegate = new PassThroughLineAggregator<T>(); |
| 34 | |
| 35 | /** |
| 36 | * Public setter for the {@link LineAggregator} to use on single items, that |
| 37 | * are not Strings. This can be used to strategise the conversion of |
| 38 | * collection and array elements to a String.<br/> |
| 39 | * |
| 40 | * @param delegate the line aggregator to set. Defaults to a pass through. |
| 41 | */ |
| 42 | public void setDelegate(LineAggregator<T> delegate) { |
| 43 | this.delegate = delegate; |
| 44 | } |
| 45 | |
| 46 | /* |
| 47 | * (non-Javadoc) |
| 48 | * @see org.springframework.batch.item.file.transform.LineAggregator#aggregate(java.lang.Object) |
| 49 | */ |
| 50 | public String aggregate(Collection<T> items) { |
| 51 | StringBuilder builder = new StringBuilder(); |
| 52 | for (T value : items) { |
| 53 | builder.append(delegate.aggregate(value) + LINE_SEPARATOR); |
| 54 | } |
| 55 | return builder.delete(builder.length()-LINE_SEPARATOR.length(),builder.length()).toString(); |
| 56 | } |
| 57 | |
| 58 | } |