/*
* @(#)CombiningAlgFactory.java
*
* Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistribution of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistribution in binary form must reproduce the above copyright
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* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
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* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
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package com.sun.xacml.combine;
import java.net.URI;
import java.util.HashMap;
import java.util.Set;
import com.sun.xacml.PolicyMetaData;
import com.sun.xacml.UnknownIdentifierException;
/**
* Provides a factory mechanism for installing and retrieving combining algorithms.
*
* @since 1.0
* @author Seth Proctor
*
* Adding generic type support by Christian Mueller (geotools)
*/
public abstract class CombiningAlgFactory {
// the proxy used to get the default factory
private static CombiningAlgFactoryProxy defaultFactoryProxy;
// the map of registered factories
private static HashMap<String, CombiningAlgFactoryProxy> registeredFactories;
/**
* static intialiazer that sets up the default factory proxy and registers the standard
* namespaces
*/
static {
CombiningAlgFactoryProxy proxy = new CombiningAlgFactoryProxy() {
public CombiningAlgFactory getFactory() {
return StandardCombiningAlgFactory.getFactory();
}
};
registeredFactories = new HashMap<String, CombiningAlgFactoryProxy>();
registeredFactories.put(PolicyMetaData.XACML_1_0_IDENTIFIER, proxy);
registeredFactories.put(PolicyMetaData.XACML_2_0_IDENTIFIER, proxy);
defaultFactoryProxy = proxy;
};
/**
* Default constructor. Used only by subclasses.
*/
protected CombiningAlgFactory() {
}
/**
* Returns the default factory. Depending on the default factory's implementation, this may
* return a singleton instance or new instances with each invokation.
*
* @return the default <code>CombiningAlgFactory</code>
*/
public static final CombiningAlgFactory getInstance() {
return defaultFactoryProxy.getFactory();
}
/**
* Returns a factory based on the given identifier. You may register as many factories as you
* like, and then retrieve them through this interface, but a factory may only be registered
* once using a given identifier. By default, the standard XACML 1.0 and 2.0 identifiers are
* regsietered to provide the standard factory.
*
* @param identifier
* the identifier for a factory
*
* @return a <code>CombiningAlgFactory</code>
*
* @throws UnknownIdentifierException
* if the given identifier isn't registered
*/
public static final CombiningAlgFactory getInstance(String identifier)
throws UnknownIdentifierException {
CombiningAlgFactoryProxy proxy = (CombiningAlgFactoryProxy) (registeredFactories
.get(identifier));
if (proxy == null)
throw new UnknownIdentifierException("Uknown CombiningAlgFactory " + "identifier: "
+ identifier);
return proxy.getFactory();
}
/**
* Sets the default factory. This does not register the factory proxy as an identifiable
* factory.
*
* @param proxy
* the <code>CombiningAlgFactoryProxy</code> to set as the new default factory proxy
*/
public static final void setDefaultFactory(CombiningAlgFactoryProxy proxy) {
defaultFactoryProxy = proxy;
}
/**
* Registers the given factory proxy with the given identifier. If the identifier is already
* used, then this throws an exception. If the identifier is not already used, then it will
* always be bound to the given proxy.
*
* @param identifier
* the identifier for the proxy
* @param proxy
* the <code>CombiningAlgFactoryProxy</code> to register with the given identifier
*
* @throws IllegalArgumentException
* if the identifier is already used
*/
public static final void registerFactory(String identifier, CombiningAlgFactoryProxy proxy)
throws IllegalArgumentException {
synchronized (registeredFactories) {
if (registeredFactories.containsKey(identifier))
throw new IllegalArgumentException("Identifier is already " + "registered as "
+ "CombiningAlgFactory: " + identifier);
registeredFactories.put(identifier, proxy);
}
}
/**
* Adds a combining algorithm to the factory. This single instance will be returned to anyone
* who asks the factory for an algorithm with the id given here.
*
* @param alg
* the combining algorithm to add
*
* @throws IllegalArgumentException
* if the algorithm is already registered
*/
public abstract void addAlgorithm(CombiningAlgorithm alg);
/**
* Adds a combining algorithm to the factory. This single instance will be returned to anyone
* who asks the factory for an algorithm with the id given here.
*
* @deprecated As of version 1.2, replaced by {@link #addAlgorithm(CombiningAlgorithm)}. The new
* factory system requires you to get a factory instance and then call the
* non-static methods on that factory. The static versions of these methods have
* been left in for now, but are slower and will be removed in a future version.
*
* @param alg
* the combining algorithm to add
*
* @throws IllegalArgumentException
* if the algorithm is already registered
*/
public static void addCombiningAlg(CombiningAlgorithm alg) {
getInstance().addAlgorithm(alg);
}
/**
* Returns the algorithm identifiers supported by this factory.
*
* @return a <code>Set</code> of <code>String</code>s
*/
public abstract Set<String> getSupportedAlgorithms();
/**
* Tries to return the correct combinging algorithm based on the given algorithm ID.
*
* @param algId
* the identifier by which the algorithm is known
*
* @return a combining algorithm
*
* @throws UnknownIdentifierException
* algId is unknown
*/
public abstract CombiningAlgorithm createAlgorithm(URI algId) throws UnknownIdentifierException;
/**
* Tries to return the correct combinging algorithm based on the given algorithm ID.
*
* @deprecated As of version 1.2, replaced by {@link #createAlgorithm(URI)}. The new factory
* system requires you to get a factory instance and then call the non-static
* methods on that factory. The static versions of these methods have been left in
* for now, but are slower and will be removed in a future version.
*
* @param algId
* the identifier by which the algorithm is known
*
* @return a combining algorithm
*
* @throws UnknownIdentifierException
* algId is unknown
*/
public static CombiningAlgorithm createCombiningAlg(URI algId)
throws UnknownIdentifierException {
return getInstance().createAlgorithm(algId);
}
}