org.apache.wookie.feature.FeatureLoader.java Source code

Introduction

Here is the source code for org.apache.wookie.feature.FeatureLoader.java

Source

/*
 *  Licensed under the Apache 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://www.apache.org/licenses/LICENSE-2.0
 *
 *  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.apache.wookie.feature;

import org.apache.commons.configuration.PropertiesConfiguration;
import org.apache.log4j.Logger;
import org.apache.wookie.beans.IServerFeature;
import org.apache.wookie.beans.util.IPersistenceManager;
import org.apache.wookie.beans.util.PersistenceCommitException;
import org.apache.wookie.beans.util.PersistenceManagerFactory;
import org.apache.wookie.w3c.util.IRIValidator;

import java.util.Iterator;

/**
 * Loads installed features when server is initialized
 *
 */
public class FeatureLoader {

    static Logger _logger = Logger.getLogger(FeatureLoader.class.getName());

    /**
     * Loads features based on the properties configuration supplied
     * @param config
     */
    @SuppressWarnings("unchecked")
    public static void loadFeatures(PropertiesConfiguration config) {
        IPersistenceManager persistenceManager = PersistenceManagerFactory.getPersistenceManager();
        persistenceManager.begin();

        // Remove existing features
        for (IServerFeature sf : persistenceManager.findAll(IServerFeature.class)) {
            persistenceManager.delete(sf);
        }

        // Add features in properties configuration
        Iterator i = config.getKeys();
        while (i.hasNext()) {
            String klass = (String) i.next();
            String name = config.getString(klass);
            _logger.info("*** klass=" + klass);
            _logger.info("*** name=" + name);
            try {
                IServerFeature sf = createFeature(name, klass);
                // Only install it if there isn't an existing
                // feature with the same name
                if (persistenceManager.findServerFeatureByName(name) == null) {
                    persistenceManager.save(sf);
                    _logger.info("Installed feature:" + name);
                } else {
                    _logger.error("Error installing feature: " + name + " was already installed");
                }

            } catch (Exception e) {
                _logger.error("Error installing feature:" + e.getMessage());
            }
        }

        try {
            persistenceManager.commit();
        } catch (PersistenceCommitException pce) {
            throw new RuntimeException("Feature loading exception: " + pce, pce);
        }
        PersistenceManagerFactory.closePersistenceManager();
    }

    /**
     * Validates a feature for the supplied parameters, or throws
     * an exception if the feature specified is not a valid.
     * @param name the name of the feature, which must be a valid IRI
     * @param klass the Class name of the feature, which must implement the IFeature interface
     */
    @SuppressWarnings("unchecked")
    public static void validateFeature(String name, String klass) throws Exception {
        // Are required parameters missing?
        if (name == null || klass == null) {
            throw new Exception("Invalid feature");
        }
        // Does the class exist?
        Class theClass;
        try {
            theClass = Class.forName(klass);
        } catch (Exception e) {
            throw new Exception("Invalid feature: class not found");
        }
        // Does the class implement IFeature?
        boolean implementsFeature = false;
        Class[] interfaces = theClass.getInterfaces();
        if (interfaces != null) {
            if (interfaces.length > 0) {
                if (interfaces[0].getName().equals("org.apache.wookie.feature.IFeature"))
                    implementsFeature = true;
            }
        }
        if (!implementsFeature)
            throw new Exception("Invalid feature: class is not a Feature class");

        // Does the feature name match that in the class?
        if (!((IFeature) theClass.newInstance()).getName().equals(name))
            throw new Exception("Invalid feature: feature name supplied and name in the class do not match");
        ;

        // Is the feature name a valid IRI?
        if (!IRIValidator.isValidIRI(name)) {
            throw new Exception("Invalid feature: name is not a valid IRI");
        }
    }

    /**
    * Returns a valid ServerFeature for the supplied parameters, or throws
    * an exception if the feature specified is not a valid ServerFeature.
    * @param name the name of the feature, which must be a valid IRI
    * @param klass the Class name of the feature, which must implement the IFeature interface
    */
    public static IServerFeature createFeature(String name, String klass) throws Exception {
        // validate feature
        validateFeature(name, klass);

        // All is well, create the SF and return it
        IPersistenceManager persistenceManager = PersistenceManagerFactory.getPersistenceManager();
        IServerFeature sf = persistenceManager.newInstance(IServerFeature.class);
        sf.setClassName(klass);
        sf.setFeatureName(name);
        return sf;
    }

}