001    /*
002     * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
003     *
004     * Project and contact information: http://www.cascading.org/
005     *
006     * This file is part of the Cascading project.
007     *
008     * Licensed under the Apache License, Version 2.0 (the "License");
009     * you may not use this file except in compliance with the License.
010     * You may obtain a copy of the License at
011     *
012     *     http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing, software
015     * distributed under the License is distributed on an "AS IS" BASIS,
016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017     * See the License for the specific language governing permissions and
018     * limitations under the License.
019     */
020    
021    package cascading.provider;
022    
023    import cascading.flow.FlowProcess;
024    
025    /**
026     * Class FactoryLoader is an implementation of a {@link ProviderLoader} and is used to load
027     * {@link CascadingFactory} instances used by internal frameworks.
028     *
029     * @see CascadingFactory
030     */
031    public class FactoryLoader extends ProviderLoader<CascadingFactory>
032      {
033      private static FactoryLoader factoryLoader;
034    
035      public synchronized static FactoryLoader getInstance()
036        {
037        if( factoryLoader == null )
038          factoryLoader = new FactoryLoader();
039    
040        return factoryLoader;
041        }
042    
043      public <Factory extends CascadingFactory> Factory loadFactoryFrom( FlowProcess flowProcess, String property, Class<Factory> defaultFactory )
044        {
045        Object value = flowProcess.getProperty( property );
046    
047        String className;
048    
049        if( value == null )
050          className = defaultFactory.getName();
051        else
052          className = value.toString();
053    
054        Factory factory = (Factory) createProvider( className ); // todo remove this cast
055    
056        if( factory != null )
057          factory.initialize( flowProcess );
058    
059        return factory;
060        }
061      }