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1   /*
2    * Copyright 2006-2013 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.core.partition.support;
18  
19  import java.io.IOException;
20  import java.util.HashMap;
21  import java.util.Map;
22  
23  import org.springframework.batch.item.ExecutionContext;
24  import org.springframework.core.io.Resource;
25  import org.springframework.util.Assert;
26  
27  /**
28   * Implementation of {@link Partitioner} that locates multiple resources and
29   * associates their file names with execution context keys. Creates an
30   * {@link ExecutionContext} per resource, and labels them as
31   * <code>{partition0, partition1, ..., partitionN}</code>. The grid size is
32   * ignored.
33   *
34   * @author Dave Syer
35   * @since 2.0
36   */
37  public class MultiResourcePartitioner implements Partitioner {
38  
39  	private static final String DEFAULT_KEY_NAME = "fileName";
40  
41  	private static final String PARTITION_KEY = "partition";
42  
43  	private Resource[] resources = new Resource[0];
44  
45  	private String keyName = DEFAULT_KEY_NAME;
46  
47  	/**
48  	 * The resources to assign to each partition. In Spring configuration you
49  	 * can use a pattern to select multiple resources.
50  	 * @param resources the resources to use
51  	 */
52  	public void setResources(Resource[] resources) {
53  		this.resources = resources;
54  	}
55  
56  	/**
57  	 * The name of the key for the file name in each {@link ExecutionContext}.
58  	 * Defaults to "fileName".
59  	 * @param keyName the value of the key
60  	 */
61  	public void setKeyName(String keyName) {
62  		this.keyName = keyName;
63  	}
64  
65  	/**
66  	 * Assign the filename of each of the injected resources to an
67  	 * {@link ExecutionContext}.
68  	 *
69  	 * @see Partitioner#partition(int)
70  	 */
71  	@Override
72  	public Map<String, ExecutionContext> partition(int gridSize) {
73  		Map<String, ExecutionContext> map = new HashMap<String, ExecutionContext>(gridSize);
74  		int i = 0;
75  		for (Resource resource : resources) {
76  			ExecutionContext context = new ExecutionContext();
77  			Assert.state(resource.exists(), "Resource does not exist: "+resource);
78  			try {
79  				context.putString(keyName, resource.getURL().toExternalForm());
80  			}
81  			catch (IOException e) {
82  				throw new IllegalArgumentException("File could not be located for: "+resource, e);
83  			}
84  			map.put(PARTITION_KEY + i, context);
85  			i++;
86  		}
87  		return map;
88  	}
89  
90  }