001    /*
002     * Sonar, open source software quality management tool.
003     * Copyright (C) 2008-2012 SonarSource
004     * mailto:contact AT sonarsource DOT com
005     *
006     * Sonar is free software; you can redistribute it and/or
007     * modify it under the terms of the GNU Lesser General Public
008     * License as published by the Free Software Foundation; either
009     * version 3 of the License, or (at your option) any later version.
010     *
011     * Sonar is distributed in the hope that it will be useful,
012     * but WITHOUT ANY WARRANTY; without even the implied warranty of
013     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014     * Lesser General Public License for more details.
015     *
016     * You should have received a copy of the GNU Lesser General Public
017     * License along with Sonar; if not, write to the Free Software
018     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
019     */
020    package org.sonar.batch.events;
021    
022    import com.google.common.collect.Lists;
023    import org.sonar.api.batch.events.EventHandler;
024    
025    import java.util.List;
026    
027    /**
028     * Dispatches {@link BatchEvent}s. Eases decoupling by allowing objects to interact without having direct dependencies upon one another, and
029     * without requiring event sources to deal with maintaining handler lists.
030     */
031    public class EventBus {
032    
033      private EventHandler[] registeredHandlers;
034    
035      public EventBus(EventHandler[] handlers) {
036        this.registeredHandlers = handlers;
037      }
038    
039      /**
040       * Fires the given event.
041       */
042      public void fireEvent(BatchEvent event) {
043        doFireEvent(event);
044      }
045    
046      private void doFireEvent(BatchEvent event) {
047        List<EventHandler> handlers = getDispatchList(event.getType());
048        for (EventHandler handler : handlers) {
049          event.dispatch(handler);
050        }
051      }
052    
053      private List<EventHandler> getDispatchList(Class<? extends EventHandler> handlerType) {
054        List<EventHandler> result = Lists.newArrayList();
055        for (EventHandler handler : registeredHandlers) {
056          if (handlerType.isAssignableFrom(handler.getClass())) {
057            result.add(handler);
058          }
059        }
060        return result;
061      }
062    
063    }