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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  package org.springframework.batch.core.listener;
17  
18  import java.util.Arrays;
19  import java.util.Collection;
20  
21  import org.springframework.batch.core.JobParameters;
22  import org.springframework.batch.core.Step;
23  import org.springframework.batch.core.StepExecution;
24  import org.springframework.batch.item.ExecutionContext;
25  
26  /**
27   * This class can be used to automatically copy items from the
28   * {@link JobParameters} to the {@link Step} {@link ExecutionContext}. A list of
29   * keys should be provided that correspond to the items in the {@link Step}
30   * {@link ExecutionContext} that should be copied.
31   * 
32   * @author Dave Syer
33   * @since 2.0
34   */
35  public class JobParameterExecutionContextCopyListener extends StepExecutionListenerSupport {
36  
37  	private Collection<String> keys = null;
38  
39  	/**
40  	 * @param keys A list of keys corresponding to items in the
41  	 * {@link JobParameters} that should be copied.
42  	 */
43  	public void setKeys(String[] keys) {
44  		this.keys = Arrays.asList(keys);
45  	}
46  
47  	/**
48  	 * Copy attributes from the {@link JobParameters} to the {@link Step}
49  	 * {@link ExecutionContext}, if not already present. The the key is already
50  	 * present we assume that a restart is in operation and the previous value
51  	 * is needed. If the provided keys are empty defaults to copy all keys in
52  	 * the {@link JobParameters}.
53  	 */
54  	@Override
55  	public void beforeStep(StepExecution stepExecution) {
56  		ExecutionContext stepContext = stepExecution.getExecutionContext();
57  		JobParameters jobParameters = stepExecution.getJobParameters();
58  		Collection<String> keys = this.keys;
59  		if (keys == null) {
60  			keys = jobParameters.getParameters().keySet();
61  		}
62  		for (String key : keys) {
63  			if (!stepContext.containsKey(key)) {
64  				stepContext.put(key, jobParameters.getParameters().get(key).getValue());
65  			}
66  		}
67  	}
68  }