    001/*
    002 * Copyright (c) 2007-2016 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  }