QueryListenersService.java

/*
 * Copyright (c) 2002-2016, Mairie de Paris
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice
 *     and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright notice
 *     and the following disclaimer in the documentation and/or other materials
 *     provided with the distribution.
 *
 *  3. Neither the name of 'Mairie de Paris' nor 'Lutece' nor the names of its
 *     contributors may be used to endorse or promote products derived from
 *     this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * License 1.0
 */
package fr.paris.lutece.portal.service.search;

import fr.paris.lutece.portal.service.util.AppLogService;

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

/**
 * QueryListenersService
 */
public final class QueryListenersService
{
    private static List<QueryEventListener> _listListeners = new ArrayList<QueryEventListener>( );
    private static volatile QueryListenersService _singleton;

    /**
     * Creates a new instance of QueryListenersService
     */
    private QueryListenersService( )
    {
    }

    /**
     * Returns the unique instance of the service
     * 
     * @return The instance of the service
     */
    public static QueryListenersService getInstance( )
    {
        if ( _singleton == null )
        {
            _singleton = new QueryListenersService( );
        }

        return _singleton;
    }

    /**
     * Register a new listener
     * 
     * @param listener
     *            The listener to register
     */
    public void registerQueryListener( QueryEventListener listener )
    {
        _listListeners.add( listener );
        AppLogService.info( "New Query Event Listener registered : " + listener.getClass( ).getName( ) );
    }

    /**
     * Notify all registered listeners
     * 
     * @param event
     *            The query event to notify
     */
    public void notifyListeners( QueryEvent event )
    {
        for ( QueryEventListener listener : _listListeners )
        {
            try
            {
                listener.processQueryEvent( event );
            }
            catch( Exception e )
            {
                // Catch any exception in order to stay in the loop to notify all listeners
                AppLogService.error( "Error while processing query event : " + e.getMessage( ), e );
            }
        }
    }
}