001/**
002 * Copyright 2005-2014 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.kew.api.extension;
017
018import org.apache.commons.lang.StringUtils;
019import org.kuali.rice.core.api.reflect.ObjectDefinition;
020import org.kuali.rice.core.api.resourceloader.GlobalResourceLoader;
021
022import javax.xml.namespace.QName;
023
024/**
025 * Contains utilities related to the loading of extension resources.
026 *
027 * @author Kuali Rice Team (rice.collab@kuali.org)
028 */
029public final class ExtensionUtils {
030
031    /**
032     * Loads the extension object for the given extension definition.
033     *
034     * @param extensionDefinition the definition of the extension to load
035     * @param <T> the type of the extension object which is to be loaded
036     *
037     * @return the loaded extension, or null if no extension was loaded for the given definition
038     */
039    public static <T> T loadExtension(ExtensionDefinitionContract extensionDefinition) {
040        return ExtensionUtils.<T>loadExtension(extensionDefinition, null);
041    }
042
043    /**
044     * Loads the extension object for the given extension definition, using the default applicationId if the given
045     * extension definition has a null applicationId.
046     *
047     * @param extensionDefinition the definition of the extension to load
048     * @param defaultApplicationId the application id to use when attempting to loading the extension if the
049     * application id on the given definition is null
050     * @param <T> the type of the extension object which is to be loaded
051     *
052     * @return the loaded extension, or null if no extension was loaded for the given definition
053     */
054    public static <T> T loadExtension(ExtensionDefinitionContract extensionDefinition, String defaultApplicationId) {
055        T extensionService = null;
056        // first check if the class name is a valid and available java class
057        String resourceDescriptor = extensionDefinition.getResourceDescriptor();
058        ObjectDefinition extensionObjectDefinition = getExtensionObjectDefinition(extensionDefinition,
059                defaultApplicationId);
060        extensionService = GlobalResourceLoader.<T>getObject(extensionObjectDefinition);
061        if (extensionService == null) {
062            // if we can't find a class, try a service
063            extensionService = GlobalResourceLoader.<T>getService(QName.valueOf(resourceDescriptor));
064        }
065        return extensionService;
066    }
067
068    private static ObjectDefinition getExtensionObjectDefinition(ExtensionDefinitionContract extensionDefinition, String defaultApplicationId) {
069        if (StringUtils.isBlank(extensionDefinition.getApplicationId()) && StringUtils.isNotBlank(defaultApplicationId)) {
070            return new ObjectDefinition(extensionDefinition.getResourceDescriptor(), defaultApplicationId);
071        } else {
072            return new ObjectDefinition(extensionDefinition.getResourceDescriptor(), extensionDefinition.getApplicationId());
073        }
074    }
075
076    private ExtensionUtils() {
077        throw new UnsupportedOperationException();
078    }
079
080}