View Javadoc

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.ArrayList;
19  import java.util.Collections;
20  import java.util.Comparator;
21  import java.util.Iterator;
22  import java.util.List;
23  
24  import org.springframework.core.Ordered;
25  import org.springframework.core.annotation.AnnotationAwareOrderComparator;
26  import org.springframework.core.annotation.AnnotationUtils;
27  import org.springframework.core.annotation.Order;
28  
29  /**
30   * @author Dave Syer
31   * 
32   */
33  class OrderedComposite<S> {
34  
35  	private List<S> unordered = new ArrayList<S>();
36  
37  	private List<S> ordered = new ArrayList<S>();
38  	
39  	@SuppressWarnings("unchecked")
40  	private Comparator<? super S> comparator = new AnnotationAwareOrderComparator();
41  
42  	private List<S> list = new ArrayList<S>();
43  
44  	/**
45  	 * Public setter for the listeners.
46  	 * 
47  	 * @param items
48  	 */
49  	public void setItems(List<? extends S> items) {
50  		unordered.clear();
51  		ordered.clear();
52  		for (S s : items) {
53  			add(s);
54  		}
55  	}
56  
57  	/**
58  	 * Register additional item.
59  	 * 
60  	 * @param item
61  	 */
62  	public void add(S item) {
63  		if (item instanceof Ordered) {
64  			if (!ordered.contains(item)) {
65  				ordered.add(item);
66  			}
67  		}
68  		else if (AnnotationUtils.isAnnotationDeclaredLocally(Order.class, item.getClass())) {
69  			if (!ordered.contains(item)) {
70  				ordered.add(item);
71  			}
72  		}
73  		else if (!unordered.contains(item)) {
74  			unordered.add(item);
75  		}
76  		Collections.sort(ordered, comparator);
77  		list.clear();
78  		list.addAll(ordered);
79  		list.addAll(unordered);
80  	}
81  
82  	/**
83  	 * Public getter for the list of items. The {@link Ordered} items come
84  	 * first, followed by any unordered ones.
85  	 * @return an iterator over the list of items
86  	 */
87  	public Iterator<S> iterator() {
88  		return new ArrayList<S>(list).iterator();
89  	}
90  
91  	/**
92  	 * Public getter for the list of items in reverse. The {@link Ordered} items
93  	 * come last, after any unordered ones.
94  	 * @return an iterator over the list of items
95  	 */
96  	public Iterator<S> reverse() {
97  		ArrayList<S> result = new ArrayList<S>(list);
98  		Collections.reverse(result);
99  		return result.iterator();
100 	}
101 
102 }