org.milyn.javabean.factory.AbstractCachingFactoryDefinitionParser Maven / Gradle / Ivy
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/*
Milyn - Copyright (C) 2006 - 2010
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License (version 2.1) as published by the Free Software
Foundation.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU Lesser General Public License for more details:
http://www.gnu.org/licenses/lgpl.txt
*/
package org.milyn.javabean.factory;
import java.util.concurrent.ConcurrentHashMap;
/**
* The AbstractCachingFactoryDefinitionParser caches all the
* factories that are create with the createFactory method. This prevents
* that factories are unnecessary created.
*
* This class is thread safe. Factories that are created with this class
* should also be thread safe.
*
* @author [email protected]
*
*/
public abstract class AbstractCachingFactoryDefinitionParser implements FactoryDefinitionParser {
private final ConcurrentHashMap> factoryCache = new ConcurrentHashMap>();
public Factory parse(String factoryDefinition) {
Factory factory = factoryCache.get(factoryDefinition);
if(factory == null) {
factory = createFactory(factoryDefinition);
if(factory == null) {
throw new NullPointerException("Null was returned by the createFactory method.");
}
// Make sure that we always return the same factory
Factory cachedFactory = factoryCache.putIfAbsent(factoryDefinition, factory);
if(cachedFactory != null) {
factory = cachedFactory;
}
}
return factory;
}
protected abstract Factory createFactory(String factoryDefinition);
}