1 /** 2 * This file Copyright (c) 2015-2018 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 }