| 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.support; |
| 18 | |
| 19 | import java.util.ArrayList; |
| 20 | import java.util.HashMap; |
| 21 | import java.util.List; |
| 22 | import java.util.Map; |
| 23 | |
| 24 | import org.springframework.batch.classify.Classifier; |
| 25 | import org.springframework.batch.classify.ClassifierSupport; |
| 26 | import org.springframework.batch.item.ItemWriter; |
| 27 | |
| 28 | /** |
| 29 | * Calls one of a collection of ItemWriters for each item, based on a router |
| 30 | * pattern implemented through the provided {@link Classifier}. |
| 31 | * |
| 32 | * The implementation is thread-safe if all delegates are thread-safe. |
| 33 | * |
| 34 | * @author Dave Syer |
| 35 | * @since 2.0 |
| 36 | */ |
| 37 | public class ClassifierCompositeItemWriter<T> implements ItemWriter<T> { |
| 38 | |
| 39 | private Classifier<T, ItemWriter<? super T>> classifier = new ClassifierSupport<T, ItemWriter<? super T>>(null); |
| 40 | |
| 41 | /** |
| 42 | * @param classifier the classifier to set |
| 43 | */ |
| 44 | public void setClassifier(Classifier<T, ItemWriter<? super T>> classifier) { |
| 45 | this.classifier = classifier; |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * Delegates to injected {@link ItemWriter} instances according to their |
| 50 | * classification by the {@link Classifier}. |
| 51 | */ |
| 52 | public void write(List<? extends T> items) throws Exception { |
| 53 | |
| 54 | Map<ItemWriter<? super T>, List<T>> map = new HashMap<ItemWriter<? super T>, List<T>>(); |
| 55 | |
| 56 | for (T item : items) { |
| 57 | ItemWriter<? super T> key = classifier.classify(item); |
| 58 | if (!map.containsKey(key)) { |
| 59 | map.put(key, new ArrayList<T>()); |
| 60 | } |
| 61 | map.get(key).add(item); |
| 62 | } |
| 63 | |
| 64 | for (ItemWriter<? super T> writer : map.keySet()) { |
| 65 | writer.write(map.get(writer)); |
| 66 | } |
| 67 | |
| 68 | } |
| 69 | |
| 70 | } |