| 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.support; |
| 17 | |
| 18 | import java.io.IOException; |
| 19 | import java.util.Comparator; |
| 20 | |
| 21 | import org.springframework.core.io.Resource; |
| 22 | import org.springframework.util.Assert; |
| 23 | |
| 24 | /** |
| 25 | * Comparator to sort resources by the file last modified time. |
| 26 | * |
| 27 | * @author Dave Syer |
| 28 | * |
| 29 | */ |
| 30 | public class LastModifiedResourceComparator implements Comparator<Resource> { |
| 31 | |
| 32 | /** |
| 33 | * Compare the two resources by last modified time, so that a sorted list of |
| 34 | * resources will have oldest first. |
| 35 | * |
| 36 | * @throws IllegalArgumentException if one of the resources doesn't exist or |
| 37 | * its last modified date cannot be determined |
| 38 | * |
| 39 | * @see Comparator#compare(Object, Object) |
| 40 | */ |
| 41 | @Override |
| 42 | public int compare(Resource r1, Resource r2) { |
| 43 | Assert.isTrue(r1.exists(), "Resource does not exist: " + r1); |
| 44 | Assert.isTrue(r2.exists(), "Resource does not exist: " + r2); |
| 45 | try { |
| 46 | long diff = r1.getFile().lastModified() - r2.getFile().lastModified(); |
| 47 | return diff > 0 ? 1 : diff < 0 ? -1 : 0; |
| 48 | } |
| 49 | catch (IOException e) { |
| 50 | throw new IllegalArgumentException("Resource modification times cannot be determined (unexpected).", e); |
| 51 | } |
| 52 | } |
| 53 | |
| 54 | } |