001/*
002 * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Nuxeo - initial API and implementation
018 *
019 * $Id$
020 */
021
022package org.nuxeo.runtime.services.event;
023
024import java.util.Arrays;
025
026import org.apache.commons.logging.Log;
027import org.apache.commons.logging.LogFactory;
028import org.nuxeo.common.xmap.annotation.XNode;
029import org.nuxeo.common.xmap.annotation.XNodeList;
030import org.nuxeo.common.xmap.annotation.XObject;
031
032/**
033 * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a>
034 */
035@XObject("listener")
036public class ListenerDescriptor {
037
038    private static final NullListener NULL_LISTENER = new NullListener();
039
040    private static final Log log = LogFactory.getLog(ListenerDescriptor.class);
041
042    @XNodeList(value = "topic", type = String[].class, componentType = String.class)
043    String[] topics;
044
045    EventListener listener;
046
047    @XNode("@class")
048    public void setListener(Class<EventListener> listenerClass) {
049        try {
050            listener = listenerClass.newInstance();
051        } catch (ReflectiveOperationException e) {
052            log.error(e);
053            listener = NULL_LISTENER;
054        }
055    }
056
057    @Override
058    public String toString() {
059        return listener + " { " + Arrays.toString(topics) + " }";
060    }
061
062}
063
064class NullListener implements EventListener {
065
066    @Override
067    public boolean aboutToHandleEvent(Event event) {
068        return false;
069    }
070
071    @Override
072    public void handleEvent(Event event) {
073    }
074
075}