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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.sample.support;
18  
19  import org.springframework.batch.core.UnexpectedJobExecutionException;
20  import org.springframework.batch.item.ItemReader;
21  
22  /**
23   * Hacked {@link ItemReader} that throws exception on a given record number
24   * (useful for testing restart).
25   * 
26   * @author Robert Kasanicky
27   * @author Lucas Ward
28   * 
29   */
30  public class ExceptionThrowingItemReaderProxy<T> implements ItemReader<T> {
31  
32  	private int counter = 0;
33  
34  	private int throwExceptionOnRecordNumber = 4;
35  
36  	private ItemReader<T> delegate;
37  
38  	/**
39  	 * @param throwExceptionOnRecordNumber The number of record on which
40  	 * exception should be thrown
41  	 */
42  	public void setThrowExceptionOnRecordNumber(int throwExceptionOnRecordNumber) {
43  		this.throwExceptionOnRecordNumber = throwExceptionOnRecordNumber;
44  	}
45  
46  	public T read() throws Exception {
47  
48  		counter++;
49  		if (counter == throwExceptionOnRecordNumber) {
50  			throw new UnexpectedJobExecutionException("Planned failure on count=" + counter);
51  		}
52  
53  		return delegate.read();
54  	}
55  
56  	public void setDelegate(ItemReader<T> delegate) {
57  		this.delegate = delegate;
58  	}
59  
60  }