com.wallabystreet.kinjo.common.resource.attribute.CompositeAttribute.java Source code

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Here is the source code for com.wallabystreet.kinjo.common.resource.attribute.CompositeAttribute.java

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/*
 *  | . _ . _
 *  |(|| )|(_) - A P2P Technology Based Grid Framework
 *        /
 *  ---
 *
 *  Copyright (c) 2005  Alexander Papaspyrou
 *
 *
 *  This file is part of kinjo.
 *
 *  kinjo is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  kinjo 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with kinjo; if not, write to the Free Software
 *  Foundation, 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

package com.wallabystreet.kinjo.common.resource.attribute;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyVetoException;
import java.util.Date;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.wallabystreet.kinjo.common.ExpiringData;
import com.wallabystreet.kinjo.common.resource.Attribute;
import com.wallabystreet.kinjo.common.resource.Diary;
import com.wallabystreet.kinjo.common.resource.Key;
import com.wallabystreet.kinjo.common.resource.Resource;
import com.wallabystreet.kinjo.common.resource.Value;

/**
 * This class defines the behaviour of attributes with children. It stores the
 * child attributes and overwrites the child-related methods of the abstract
 * superclass.
 * 
 * @author Alexander Papaspyrou
 * @version $Revision$, $Date$
 */
public class CompositeAttribute extends AbstractAttribute {

    /**
     * The default log facility for this class, using the <a
     * href="http://jakarta.apache.org/commons/logging/">Jakarta "commons
     * logging" API</a>.
     * 
     * @see org.apache.commons.logging.Log
     * @see org.apache.commons.logging.LogFactory
     */
    final private static Log log = LogFactory.getLog(CompositeAttribute.class);

    /**
     * Stores the components of this composite.
     */
    private List<Attribute> descendants;

    /**
     * Creates a new instance of this type, using the given parameters.
     * 
     * @param parent
     *            The parent of this attribute.
     * @param k
     *            The identifier of this attribute.
     */
    public CompositeAttribute(Attribute parent, Key k) {
        this(null, parent, k);
        this.descendants = new LinkedList<Attribute>();
    }

    /**
     * Creates a new instance of this type, using the given parameters.
     * 
     * @param r
     *            The resource this attribute belongs to.
     * @param parent
     *            The parent of this attribute.
     * @param k
     *            The identifier of this attribute.
     */
    public CompositeAttribute(Resource r, Attribute parent, Key k) {
        super(r, parent, k);
        this.descendants = new LinkedList<Attribute>();
    }

    /**
     * Because composite attributes have no expiration date (and thus cannot
     * expire), this method always returns <code>null</code>.
     * 
     * @return <code>null</code>.
     * @see com.wallabystreet.kinjo.common.ExpiringData#getExpirationDate()
     */
    public Date getExpirationDate() {
        log.info("never expires");
        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.ExpiringData#hasExpired()
     */
    public boolean hasExpired() {
        log.info("never expires");
        return false;
    }

    /**
     * Notifies all children to update themselves.
     * 
     * @see com.wallabystreet.kinjo.common.ExpiringData#update()
     */
    public void update() {
        for (ExpiringData child : this.descendants) {
            child.update();
        }
    }

    /**
     * Notifies all children to flush themselves.
     * 
     * @see com.wallabystreet.kinjo.common.ExpiringData#flush()
     */
    public void flush() {
        for (ExpiringData child : this.descendants) {
            child.flush();
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.resource.Attribute#getValue()
     */
    public Value getValue() {
        log.info("no value");
        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.resource.Attribute#setValue(edu.udo.kinjo.common.resource.Value)
     */
    public void setValue(Value v) throws UnsupportedOperationException, PropertyVetoException {
        UnsupportedOperationException e = new UnsupportedOperationException(
                "composite, no child: " + this.toString());
        log.info("no value", e);
        throw e;
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.resource.Attribute#getDiary()
     */
    public Diary getDiary() {
        // TODO Not implemented yet.
        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.Ancestor#descendants()
     */
    public Iterator<Attribute> descendants() {
        return descendants.isEmpty() ? null : descendants.iterator();
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.Ancestor#addDescendant(T)
     */
    public void addDescendant(Attribute descendant) throws PropertyVetoException {
        this.observers.fireVetoableChange(new PropertyChangeEvent(this, "descendant", null, descendant));
        if (log.isDebugEnabled()) {
            log.debug("adding descendant: " + descendant.toString());
        }
        descendants.add(descendant);
    }

    /*
     * (non-Javadoc)
     * 
     * @see edu.udo.kinjo.common.Ancestor#removeDescendant(T)
     */
    public void removeDescendant(Attribute descendant) throws PropertyVetoException {
        this.observers.fireVetoableChange(new PropertyChangeEvent(this, "child", null, descendant));
        if (log.isDebugEnabled()) {
            log.debug("removing descendant: " + descendant.toString());
        }
        this.descendants.remove(descendant);
    }

}