/*
* Copyright 2006-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.item.file.transform;
import java.util.Collection;
/**
* An implementation of {@link LineAggregator} that concatenates a collection of
* items of a common type with the system line separator.
*
* @author Dave Syer
*
*/
public class RecursiveCollectionLineAggregator<T> implements LineAggregator<Collection<T>> {
private static final String LINE_SEPARATOR = System.getProperty("line.separator");
private LineAggregator<T> delegate = new PassThroughLineAggregator<T>();
/**
* Public setter for the {@link LineAggregator} to use on single items, that
* are not Strings. This can be used to strategise the conversion of
* collection and array elements to a String.<br>
*
* @param delegate the line aggregator to set. Defaults to a pass through.
*/
public void setDelegate(LineAggregator<T> delegate) {
this.delegate = delegate;
}
/*
* (non-Javadoc)
* @see org.springframework.batch.item.file.transform.LineAggregator#aggregate(java.lang.Object)
*/
@Override
public String aggregate(Collection<T> items) {
StringBuilder builder = new StringBuilder();
for (T value : items) {
builder.append(delegate.aggregate(value) + LINE_SEPARATOR);
}
return builder.delete(builder.length()-LINE_SEPARATOR.length(),builder.length()).toString();
}
}