ObjectDescription.java

/* ========================================================================
 * JCommon : a free general purpose class library for the Java(tm) platform
 * ========================================================================
 *
 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
 * 
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * This library is free software; you can redistribute it and/or modify it 
 * under the terms of the GNU Lesser General Public License as published by 
 * the Free Software Foundation; either version 2.1 of the License, or 
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
 * USA.  
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * 
 * ----------------------
 * ObjectDescription.java
 * ----------------------
 * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: ObjectDescription.java,v 1.3 2005/11/14 11:03:12 mungady Exp $
 *
 * Changes (from 19-Feb-2003)
 * -------------------------
 * 19-Feb-2003 : Added standard header and Javadocs (DG);
 * 29-Apr-2003 : Distilled from the JFreeReport project and moved into JCommon
 *
 */

package org.jfree.xml.factory.objects;

import java.io.Serializable;
import java.util.Iterator;

import org.jfree.util.Configuration;

/**
 * An interface for object descriptions.
 *
 * @author Thomas Morgner
 */
public interface ObjectDescription extends Serializable {

    /**
     * Returns a parameter definition. If the parameter is invalid, this
     * function returns null.
     *
     * @param name  the definition name.
     *
     * @return The parameter class or null, if the parameter is not defined.
     */
    public Class getParameterDefinition(String name);

    /**
     * Sets the value of a parameter.
     *
     * @param name  the parameter name.
     * @param value  the parameter value.
     */
    public void setParameter(String name, Object value);

    /**
     * Returns the value of a parameter.
     *
     * @param name  the parameter name.
     *
     * @return The value.
     */
    public Object getParameter(String name);

    /**
     * Returns an iterator the provides access to the parameter names. This
     * returns all _known_ parameter names, the object description may accept
     * additional parameters.
     *
     * @return The iterator.
     */
    public Iterator getParameterNames();

    /**
     * Returns the object class.
     *
     * @return The Class.
     */
    public Class getObjectClass();

    /**
     * Creates an object based on the description.
     *
     * @return The object.
     */
    public Object createObject();

    /**
     * Returns a cloned instance of the object description. The contents
     * of the parameter objects collection are cloned too, so that any
     * already defined parameter value is copied to the new instance.
     * <p>
     * Parameter definitions are not cloned, as they are considered read-only.
     * <p>
     * The newly instantiated object description is not configured. If it
     * need to be configured, then you have to call configure on it.
     *
     * @return A cloned instance.
     */
    public ObjectDescription getUnconfiguredInstance();

    /**
     * Returns a cloned instance of the object description. The contents
     * of the parameter objects collection are cloned too, so that any
     * already defined parameter value is copied to the new instance.
     * <p>
     * Parameter definitions are not cloned, as they are considered read-only.
     *
     * @return A cloned instance.
     */
    public ObjectDescription getInstance();

    /**
     * Sets the parameters of this description object to match the supplied object.
     *
     * @param o  the object.
     *
     * @throws ObjectFactoryException if there is a problem while reading the
     * properties of the given object.
     */
    public void setParameterFromObject(Object o) throws ObjectFactoryException;


    /**
     * Configures this factory. The configuration contains several keys and
     * their defined values. The given reference to the configuration object
     * will remain valid until the report parsing or writing ends.
     * <p>
     * The configuration contents may change during the reporting.
     *
     * @param config the configuration, never null
     */
    public void configure(Configuration config);

    /**
     * Compares whether two object descriptions are equal.
     *
     * @param o the other object.
     * @return true, if both object desciptions describe the same object, false otherwise.
     */
    public boolean equals (Object o);


    /**
     * Computes the hashCode for this ClassFactory. As equals() must be implemented,
     * a corresponding hashCode() should be implemented as well.
     *
     * @return the hashcode.
     */
    public int hashCode();

}