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 @Override
51 public String aggregate(Collection<T> items) {
52 StringBuilder builder = new StringBuilder();
53 for (T value : items) {
54 builder.append(delegate.aggregate(value) + LINE_SEPARATOR);
55 }
56 return builder.delete(builder.length()-LINE_SEPARATOR.length(),builder.length()).toString();
57 }
58
59 }