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
021package cascading.provider;
022
023import 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 */
031public 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  }