001    /*
002     * Copyright (C) 2010 eXo Platform SAS.
003     *
004     * This is free software; you can redistribute it and/or modify it
005     * under the terms of the GNU Lesser General Public License as
006     * published by the Free Software Foundation; either version 2.1 of
007     * the License, or (at your option) any later version.
008     *
009     * This software is distributed in the hope that it will be useful,
010     * but WITHOUT ANY WARRANTY; without even the implied warranty of
011     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012     * Lesser General Public License for more details.
013     *
014     * You should have received a copy of the GNU Lesser General Public
015     * License along with this software; if not, write to the Free
016     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018     */
019    package org.crsh.plugin;
020    
021    import org.slf4j.Logger;
022    import org.slf4j.LoggerFactory;
023    
024    import java.util.ArrayList;
025    import java.util.ServiceConfigurationError;
026    import java.util.ServiceLoader;
027    
028    /**
029     * An implementation of {@link PluginDiscovery} based on {@link ServiceLoader}.
030     * 
031     * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
032     */
033    public class ServiceLoaderDiscovery implements PluginDiscovery {
034    
035      /** . */
036      private static final Logger log = LoggerFactory.getLogger(PluginManager.class);
037    
038      /** . */
039      private final ClassLoader classLoader;
040    
041      /**
042       * Create a new instance.
043       *
044       * @param classLoader the loader for the discovery
045       * @throws NullPointerException if the loader argument is null
046       */
047      public ServiceLoaderDiscovery(ClassLoader classLoader) throws NullPointerException {
048        if (classLoader == null) {
049          throw new NullPointerException();
050        }
051    
052        //
053        this.classLoader = classLoader;
054      }
055    
056      public Iterable<CRaSHPlugin<?>> getPlugins() {
057    
058        //
059        ArrayList<CRaSHPlugin<?>> plugins = new ArrayList<CRaSHPlugin<?>>();
060        try {
061          ServiceLoader<CRaSHPlugin> loader = ServiceLoader.load(CRaSHPlugin.class, classLoader);
062          for (CRaSHPlugin<?> plugin : loader) {
063            log.info("Loaded plugin " + plugin);
064            plugins.add(plugin);
065          }
066        }
067        catch (ServiceConfigurationError e) {
068          log.error("Could not load plugins", e);
069        }
070    
071        //
072        return plugins;
073      }
074    }