LifecycleSupport.java

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package org.apache.catalina.util;

import org.apache.catalina.Lifecycle;
import org.apache.catalina.LifecycleEvent;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleListener;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;


/**
 * Support class to assist in firing LifecycleEvent notifications to
 * registered LifecycleListeners.
 *
 * @author Craig R. McClanahan
 * @version $Id: LifecycleSupport.java,v 1.2 2005/12/08 01:28:17 kchung Exp $
 */

public final class LifecycleSupport {


    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new LifecycleSupport object associated with the specified
     * Lifecycle component.
     *
     * @param lifecycle The Lifecycle component that will be the source
     *  of events that we fire
     */
    public LifecycleSupport(Lifecycle lifecycle) {
        super();
        this.lifecycle = lifecycle;
    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The source component for lifecycle events that we will fire.
     */
    private Lifecycle lifecycle = null;


    /**
     * The list of registered LifecycleListeners for event notifications.
     */
    private List<LifecycleListener> listeners =
        new ArrayList<LifecycleListener>();


    // --------------------------------------------------------- Public Methods


    /**
     * Add a lifecycle event listener to this component.
     *
     * @param listener The listener to add
     */
    public void addLifecycleListener(LifecycleListener listener) {
        synchronized (listeners) {
            listeners.add(listener);
        }
    }


    /**
     * Gets the (possibly empty) list of lifecycle listeners associated
     * with this LifecycleSupport instance.
     */
    public List<LifecycleListener> findLifecycleListeners() {
        return listeners;
    }


    /**
     * Notify all lifecycle event listeners that a particular event has
     * occurred for this Container.  The default implementation performs
     * this notification synchronously using the calling thread.
     *
     * @param type Event type
     * @param data Event data
     */
    public void fireLifecycleEvent(String type, Object data)
            throws LifecycleException {


        LifecycleListener[] listenersArray = null;

        synchronized (listeners) {
            if (listeners.isEmpty()) {
                return;
            }
            listenersArray = listeners.toArray(
                    new LifecycleListener[listeners.size()]);
        }

        LifecycleEvent event = new LifecycleEvent(lifecycle, type, data);

        for (int i = 0; i < listenersArray.length; i++) {
            listenersArray[i].lifecycleEvent(event);
        }

    }


    /**
     * Remove a lifecycle event listener from this component.
     *
     * @param listener The listener to remove
     */
    public void removeLifecycleListener(LifecycleListener listener) {
        synchronized (listeners) {
            listeners.remove(listener);
        }
    }


    /**
     * Removes any lifecycle event listeners from this LifecycleSupport
     * instance.
     */
    public void removeLifecycleListeners() {
        listeners.clear();
    }

}