001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.monitoring.web.discovery;
018    
019    import org.apache.commons.monitoring.gauges.Gauge;
020    
021    import javax.servlet.ServletContextEvent;
022    import javax.servlet.ServletContextListener;
023    
024    public class GaugeDiscoveryListener implements ServletContextListener {
025        private Gauge.LoaderHelper helper;
026    
027        @Override
028        public void contextInitialized(final ServletContextEvent sce) {
029            final String prefixesStr = sce.getServletContext().getInitParameter("monitoring.discovery.packages");
030            final String[] prefixes;
031            if (prefixesStr != null) {
032                prefixes = prefixesStr.split(",");
033            } else {
034                prefixes = new String[0];
035            }
036            helper = new Gauge.LoaderHelper("true".equals(sce.getServletContext().getInitParameter("monitoring.discovery.exclude-parent")), prefixes);
037        }
038    
039        @Override
040        public void contextDestroyed(final ServletContextEvent sce) {
041            helper.destroy();
042        }
043    }