/** * Licensed to The Apereo Foundation under one or more contributor license * agreements. See the NOTICE file distributed with this work for additional * information regarding copyright ownership. * * * The Apereo Foundation licenses this file to you under the Educational * Community License, Version 2.0 (the "License"); you may not use this file * except in compliance with the License. You may obtain a copy of the License * at: * * http://opensource.org/licenses/ecl2.txt * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. * */ package org.opencastproject.mediapackage; import org.opencastproject.util.ConfigurationException; /** * Factory to retrieve instances of a media package builder. Use the static method {@link #newInstance()} to obtain a * reference to a concrete implementation of a <code>MediaPackageBuilderFactory</code>. This instance can then be used * to create or load media packages. * <p> * The factory can be configured by specifying the concrete implementation class through the system property * <code>org.opencastproject.mediapackage.builder</code>. * </p> */ public final class MediaPackageBuilderFactory { /** Class name for the default media package builder */ private static final String BUILDER_CLASS = "org.opencastproject.mediapackage.MediaPackageBuilderImpl"; /** Name of the system property */ public static final String PROPERTY_NAME = "org.opencastproject.mediapackage.builder"; /** The implementation class name */ private static String builderClassName = BUILDER_CLASS; /** The singleton instance of this factory */ private static final MediaPackageBuilderFactory factory = new MediaPackageBuilderFactory(); /** * Private method to create a new media package builder factory. */ private MediaPackageBuilderFactory() { String className = System.getProperty(PROPERTY_NAME); if (className != null) { builderClassName = className; } } /** * Returns an instance of a MediaPackageBuilderFactory. * * @return the media package builder factory * @throws ConfigurationException * if the factory cannot be instantiated */ public static MediaPackageBuilderFactory newInstance() throws ConfigurationException { return factory; } /** * Factory method that returns an instance of a media package builder. * <p> * It uses the following ordered lookup procedure to determine which implementation of the {@link MediaPackageBuilder} * interface to use: * <ul> * <li>Implementation specified using the <code>org.opencastproject.mediapackage.builder</code> system property</li> * <li>Platform default implementation</li> * </ul> * * @return the media package builder * @throws ConfigurationException * If the builder cannot be instantiated */ public MediaPackageBuilder newMediaPackageBuilder() throws ConfigurationException { MediaPackageBuilder builder = null; try { Class<?> builderClass = Class.forName(builderClassName); builder = (MediaPackageBuilder) builderClass.newInstance(); } catch (ClassNotFoundException e) { throw new ConfigurationException("Class not found while creating media package builder: " + e.getMessage(), e); } catch (InstantiationException e) { throw new ConfigurationException("Instantiation exception while creating media package builder: " + e.getMessage(), e); } catch (IllegalAccessException e) { throw new ConfigurationException("Access exception while creating media package builder: " + e.getMessage(), e); } return builder; } }