org.ccsds.moims.mo.mal.accesscontrol.MALAccessControlFactory Maven / Gradle / Ivy

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An implementation of the Java API for the CCSDS MAL
There is a newer version: 10.1
/* ----------------------------------------------------------------------------
 * Copyright (C) 2013      European Space Agency
 *                         European Space Operations Centre
 *                         Darmstadt
 *                         Germany
 * ----------------------------------------------------------------------------
 * System                : CCSDS MO MAL Java API
 * ----------------------------------------------------------------------------
 * Licensed under the European Space Agency Public License, Version 2.0
 * You may not use this file except in compliance with the License.
 *
 * Except as expressly set forth in this License, the Software is provided to
 * You on an "as is" basis and without warranties of any kind, including without
 * limitation merchantability, fitness for a particular purpose, absence of
 * defects or errors, accuracy or non-infringement of intellectual property rights.
 * 
 * See the License for the specific language governing permissions and
 * limitations under the License. 
 * ----------------------------------------------------------------------------
 */
package org.ccsds.moims.mo.mal.accesscontrol;

import java.util.HashMap;
import java.util.Map;
import org.ccsds.moims.mo.mal.MALException;

/**
 * The MALAccessControlFactory class enables the MAL layer to create and
 * configure MALAccessControl instances. The class provides a static factory
 * class repository that maps the MALAccessControlFactory implementation classes
 * to their class names.
 */
public abstract class MALAccessControlFactory {

    /**
     * The system property that resolves the specific MALAccessControlFactory
     * class name.
     */
    public static final String FACTORY_PROP_NAME = "org.ccsds.moims.mo.mal.accesscontrol.factory.class";
    private static final Map _FACTORY_MAP = new HashMap<>();

    /**
     * The method allows an implementation to register the class of a specific
     * MALAccessControlFactory. NOTE – This method may be useful in environments
     * where several class loaders are involved (e.g., OSGi platforms).
     *
     * @param factoryClass Class extending MALAccessControlFactory
     * @throws IllegalArgumentException if the argument does not extend
     * MALAccessControlFactory
     */
    public static void registerFactoryClass(final java.lang.Class factoryClass)
            throws IllegalArgumentException {
        if (!MALAccessControlFactory.class.isAssignableFrom(factoryClass)) {
            throw new IllegalArgumentException("Not compliant: " + factoryClass.getName());
        }

        _FACTORY_MAP.put(factoryClass.getName(), factoryClass);
    }

    /**
     * The method allows an implementation to deregister the class of a specific
     * MALAccessControlFactory.
     *
     * @param factoryClass The class to deregister
     * @throws IllegalArgumentException if the argument does not extend
     * MALAccessControlFactory
     */
    public static void deregisterFactoryClass(final java.lang.Class factoryClass)
            throws IllegalArgumentException {
        if (!MALAccessControlFactory.class.isAssignableFrom(factoryClass)) {
            throw new IllegalArgumentException("Not compliant: " + factoryClass.getName());
        }

        if (null != factoryClass) {
            _FACTORY_MAP.remove(factoryClass.getName());
        }
    }

    /**
     * The method returns a MALAccessControlFactory instance.
     *
     * @return The new factory.
     * @throws MALException If an error detected during instantiation.
     */
    public static MALAccessControlFactory newFactory() throws MALException {
        final String className = System.getProperty(FACTORY_PROP_NAME);
        try {
            if (null != className) {
                Class factoryClass;

                if (_FACTORY_MAP.containsKey(className)) {
                    factoryClass = _FACTORY_MAP.get(className);
                } else {
                    factoryClass = Class.forName(className);
                    registerFactoryClass(factoryClass);
                }

                return (MALAccessControlFactory) factoryClass.newInstance();
            }
        } catch (ClassNotFoundException exc) {
            throw new MALException(exc.getLocalizedMessage(), exc);
        } catch (InstantiationException exc) {
            throw new MALException(exc.getLocalizedMessage(), exc);
        } catch (IllegalAccessException exc) {
            throw new MALException(exc.getLocalizedMessage(), exc);
        }

        return null;
    }

    /**
     * Creates an instance of an access control object.
     *
     * @param properties The QoS properties to use.
     * @return The new access control instance.
     * @throws MALException If an error detected during instantiation.
     */
    public abstract MALAccessControl createAccessControl(java.util.Map properties) throws MALException;
}