1 /**
2 * This file Copyright (c) 2015 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.cms.util;
35
36 import javax.jcr.RepositoryException;
37 import javax.jcr.observation.Event;
38 import javax.jcr.observation.EventIterator;
39 import javax.jcr.observation.EventListener;
40
41 import org.apache.jackrabbit.JcrConstants;
42 import org.apache.jackrabbit.commons.iterator.EventIteratorAdapter;
43 import org.apache.jackrabbit.commons.iterator.FilteredRangeIterator;
44 import org.apache.jackrabbit.commons.predicate.Predicate;
45 import org.slf4j.Logger;
46 import org.slf4j.LoggerFactory;
47
48 /**
49 * The FilteredEventListener decorates a given {@link EventListener} and allows to ignore specific {@link Event Events}
50 * according to a given {@link Predicate}.
51 */
52 public class FilteredEventListener implements EventListener {
53
54 private static final Logger log = LoggerFactory.getLogger(FilteredEventListener.class);
55
56 /**
57 * Predicate evaluating to false if the path for a given Event starts with '/jcr:system'.
58 * This is especially convenient when observing "/", to discard events generated for jcr:system,
59 * which is "shared" across all workspaces.
60 *
61 * @see ObservationUtil#registerChangeListener(String, String, boolean, String[], int, EventListener)
62 */
63 public static final Predicate JCR_SYSTEM_EXCLUDING_PREDICATE = new Predicate() {
64 @Override
65 public boolean evaluate(Object event) {
66 try {
67 return !((Event) event).getPath().startsWith("/" + JcrConstants.JCR_SYSTEM);
68 } catch (RepositoryException e) {
69 log.error("Could not get path of event {}.", event);
70 return false;
71 }
72 }
73 };
74
75 private final EventListener eventListener;
76 private final Predicate predicate;
77
78 public FilteredEventListener(EventListener eventListener, Predicate predicate) {
79 this.eventListener = eventListener;
80 this.predicate = predicate;
81 }
82
83 @Override
84 public void onEvent(EventIterator events) {
85 EventIterator filteredEvents = new EventIteratorAdapter(new FilteredRangeIterator(events, predicate));
86 eventListener.onEvent(filteredEvents);
87 }
88 }