verdandi.plugin.PluginLoader.java Source code

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Here is the source code for verdandi.plugin.PluginLoader.java

Source

/*******************************************************************************
 * Copyright 2010 Olaf Sebelin
 * 
 * This file is part of Verdandi.
 * 
 * Verdandi is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * Verdandi is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with Verdandi.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package verdandi.plugin;

import java.io.File;
import java.io.FilenameFilter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;
import java.util.ServiceLoader;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import verdandi.VerdandiConfiguration;
import verdandi.model.VerdandiModel;

public class PluginLoader {

    private static final Log LOG = LogFactory.getLog(PluginLoader.class);

    private VerdandiConfiguration conf;

    private List<VerdandiPlugin> plugins = new ArrayList<VerdandiPlugin>();

    public PluginLoader() {
        super();
        this.conf = VerdandiModel.getConf();
        loadPlugins();
    }

    private boolean classAlreadyLoaded(Class<? extends VerdandiPlugin> pluginclass) {
        LOG.debug("Checking, if " + pluginclass.getName() + " is loaded");

        for (VerdandiPlugin loaded : plugins) {
            if (loaded.getClass().getName().equals(pluginclass.getName())) {
                LOG.info("Class already loaded. Will not load again: " + pluginclass.getName());
                return true;
            }
        }
        return false;

    }

    private void load(ClassLoader classLoader) {
        ServiceLoader<VerdandiPlugin> serviceLoader = ServiceLoader.load(VerdandiPlugin.class, classLoader);
        for (VerdandiPlugin verdandiPlugin : serviceLoader) {
            if (!classAlreadyLoaded(verdandiPlugin.getClass())) {
                plugins.add(verdandiPlugin);
            }
            LOG.debug("Loaded plugin " + verdandiPlugin.getClass().getCanonicalName());
        }

    }

    public void loadPlugins() {

        LOG.debug("Loading system plugins");
        load(Thread.currentThread().getContextClassLoader());

        LOG.debug("Now loading plugins from plugin dir " + conf.getPluginDir().getAbsolutePath());
        File pluginJars[] = conf.getPluginDir().listFiles(new FilenameFilter() {
            public boolean accept(File dir, String name) {
                return name.toLowerCase().endsWith(".jar");
            }
        });
        if (pluginJars != null) {

            for (File pluginJar : pluginJars) {
                try {
                    ClassLoader pluginLoader = new URLClassLoader(new URL[] { pluginJar.toURI().toURL() },
                            Thread.currentThread().getContextClassLoader());
                    LOG.debug("Loading plugins from " + pluginJar.getName());
                    load(pluginLoader);
                } catch (MalformedURLException e) {
                    LOG.error("Cannot load casses from " + pluginJar.getAbsolutePath(), e);
                }
            }
        } else {
            LOG.debug("No plugin jars found in " + conf.getPluginDir().getAbsolutePath());
        }

    }

    public List<VerdandiPlugin> getPlugins() {
        return plugins;
    }

}