Pithos_GSS » GSS

/*

 * Copyright 2006, 2007, 2008, 2009 Electronic Business Systems Ltd.

 *

 * This file is part of GSS.

 *

 * GSS 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.

 *

 * GSS 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 GSS.  If not, see <http://www.gnu.org/licenses/>.

 */

package org.gss_project.gss.server.configuration;

import java.io.File;

import java.net.MalformedURLException;

import java.net.URL;

import org.apache.commons.configuration.BaseConfiguration;

import org.apache.commons.configuration.ConfigurationException;

import org.apache.commons.configuration.ConfigurationUtils;

import org.apache.commons.configuration.DataConfiguration;

import org.apache.commons.configuration.PropertiesConfiguration;

import org.apache.commons.configuration.reloading.FileChangedReloadingStrategy;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

/**

 * Singleton that loads properties from gss.properties and

 * makes them available to all

 *

 * @author droutsis

 */

public final class GSSConfigurationFactory {

        /**

         * The logger.

         */

        private static Log logger = LogFactory.getLog(GSSConfigurationFactory.class);

        /**

         * The filename of the file containing system properties.

         */

        private static String configFilename = "gss.properties";

        /**

         * The (single) configuration object

         */

        private static DataConfiguration configuration = null;

        /**

         * Exists only to defeat instantiation.

         */

        private GSSConfigurationFactory() {

        }

        /**

         * Because multiple classloaders are commonly used in many situations -

         * including servlet containers - you can wind up with multiple singleton instances

         * no matter how carefully you've implemented your singleton classes.

         * If you want to make sure the same classloader loads your singletons,

         * you must specify the classloader yourself; for example:

         *

         * @param classname

         * @return

         * @throws ClassNotFoundException

         */

        private static Class getClass(String classname) throws ClassNotFoundException {

              ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

              if(classLoader == null)

                 classLoader = GSSConfigurationFactory.class.getClassLoader();

              return classLoader.loadClass(classname);

        }

        /**

         * @return the configuration object

         */

        public synchronized static DataConfiguration getConfiguration() {

                try {

                        if (configuration==null) {

                                PropertiesConfiguration gssConfig = (PropertiesConfiguration) getClass(PropertiesConfiguration.class.getCanonicalName()).newInstance();

                                gssConfig.setBasePath("");

                                gssConfig.setFileName(configFilename);

                                gssConfig.setEncoding("ISO-8859-7");

                                // Set automatic reloading.

                                gssConfig.setReloadingStrategy(new VfsFileChangedReloadingStrategy());

                                gssConfig.load();

                                // Decorator.

                                configuration = new DataConfiguration(gssConfig);

                        }

                        return configuration;

                }

                catch (ClassNotFoundException e) {

                        // Use empty configuration, so we get no NPE but default values

                        configuration = new DataConfiguration(new BaseConfiguration());

                        logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);

                        return configuration;

                } catch (InstantiationException e) {

                        // Use empty configuration, so we get no NPE but default values

                        configuration = new DataConfiguration(new BaseConfiguration());

                        logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);

                        return configuration;

                } catch (IllegalAccessException e) {

                        // Use empty configuration, so we get no NPE but default values

                        configuration = new DataConfiguration(new BaseConfiguration());

                        logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);

                        return configuration;

                } catch (ConfigurationException e) {

                        // Use empty configuration, so we get no NPE but default values

                        configuration = new DataConfiguration(new BaseConfiguration());

                        logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);

                        return configuration;

                }

        }

        /**

         * Extends the FileChangedReloadingStrategy from Commons Configuration, adding

         * support for files in JBoss MC VFS.

         *

         * @author past

         */

        private static class VfsFileChangedReloadingStrategy extends FileChangedReloadingStrategy {

            /** Constant for the jar URL protocol.*/

            private static final String JAR_PROTOCOL = "jar";

            /** Constant for the JBoss MC VFSFile URL protocol.*/

            private static final String VFSFILE_PROTOCOL = "vfsfile";

            @Override

                protected File getFile()

            {

                return configuration.getURL() != null ? fileFromURL(configuration

                        .getURL()) : configuration.getFile();

            }

            /**

             * Helper method for transforming a URL into a file object. This method

             * handles file: and jar: URLs, as well as JBoss VFS-specific vfsfile:

             * URLs.

             *

             * @param url the URL to be converted

             * @return the resulting file or <b>null </b>

             */

            private File fileFromURL(URL url)

            {

                if (VFSFILE_PROTOCOL.equals(url.getProtocol()))

                {

                    String path = url.getPath();

                    try

                    {

                        return ConfigurationUtils.fileFromURL(new URL("file:" + path));

                    }

                    catch (MalformedURLException mex)

                    {

                        return null;

                    }

                }

                else if (JAR_PROTOCOL.equals(url.getProtocol()))

                {

                    String path = url.getPath();

                    try

                    {

                        return ConfigurationUtils.fileFromURL(new URL(path.substring(0,

                                path.indexOf('!'))));

                    }

                    catch (MalformedURLException mex)

                    {

                        return null;

                    }

                } else

                                return ConfigurationUtils.fileFromURL(url);

            }

        }

}