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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.List;
20  
21  import org.springframework.batch.item.ItemProcessor;
22  import org.springframework.beans.factory.InitializingBean;
23  import org.springframework.util.Assert;
24  
25  /**
26   * Composite {@link ItemProcessor} that passes the item through a sequence of
27   * injected <code>ItemTransformer</code>s (return value of previous
28   * transformation is the entry value of the next).<br/>
29   * <br/>
30   * 
31   * Note the user is responsible for injecting a chain of {@link ItemProcessor} s
32   * that conforms to declared input and output types.
33   * 
34   * @author Robert Kasanicky
35   */
36  public class CompositeItemProcessor<I, O> implements ItemProcessor<I, O>, InitializingBean {
37  
38  	private List<ItemProcessor<Object, Object>> delegates;
39  
40      @Override
41  	@SuppressWarnings("unchecked")
42  	public O process(I item) throws Exception {
43  		Object result = item;
44  
45  		for (ItemProcessor<Object, Object> delegate : delegates) {
46  			if (result == null) {
47  				return null;
48  			}
49  			result = delegate.process(result);
50  		}
51  		return (O) result;
52  	}
53  
54      @Override
55  	public void afterPropertiesSet() throws Exception {
56  		Assert.notNull(delegates, "The 'delgates' may not be null");
57  		Assert.notEmpty(delegates, "The 'delgates' may not be empty");
58  	}
59  
60  	public void setDelegates(List<ItemProcessor<Object, Object>> delegates) {
61  		this.delegates = delegates;
62  	}
63  
64  }