001    /*****************************************************************************
002     * Copyright (C) PicoContainer Organization. All rights reserved.            *
003     * ------------------------------------------------------------------------- *
004     * The software in this package is published under the terms of the BSD      *
005     * style license a copy of which has been included with this distribution in *
006     * the LICENSE.txt file.                                                     *
007     *****************************************************************************/
008    package org.picocontainer.lifecycle;
009    
010    import java.io.Serializable;
011    
012    import org.picocontainer.ComponentMonitor;
013    import org.picocontainer.ComponentMonitorStrategy;
014    import org.picocontainer.LifecycleStrategy;
015    
016    /**
017     * Abstract base class for lifecycle strategy implementation supporting a {@link ComponentMonitor}.
018     *
019     * @author Jörg Schaible
020     */
021    public abstract class AbstractMonitoringLifecycleStrategy implements LifecycleStrategy, ComponentMonitorStrategy, Serializable {
022    
023            /**
024             * Component monitor that receives lifecycle state.
025             */
026        private ComponentMonitor componentMonitor;
027    
028    
029        /**
030         * Construct a AbstractMonitoringLifecycleStrategy.
031         *
032         * @param monitor the componentMonitor to use
033         * @throws NullPointerException if the monitor is <code>null</code>
034         */
035        public AbstractMonitoringLifecycleStrategy(final ComponentMonitor monitor) {
036            changeMonitor(monitor);
037        }
038    
039        /**
040         * Swaps the current monitor with a replacement.
041         * @param monitor The new monitor.
042         * @throws NullPointerException if the passed in monitor is null.
043         */
044        public void changeMonitor(final ComponentMonitor monitor) {
045            if (monitor == null) {
046                throw new NullPointerException("Monitor is null");
047            }
048            this.componentMonitor = monitor;
049        }
050    
051        /**
052         * Retrieves access to the current monitor.
053         */
054        public ComponentMonitor currentMonitor() {
055            return componentMonitor;
056        }
057    
058    }