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Guise™ Internet application framework.
There is a newer version: 0.5.3
/*
 * Copyright © 2005-2008 GlobalMentor, Inc. 
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.guise.framework.component.transfer;

import static java.util.Objects.*;

import com.globalmentor.io.*;
import com.globalmentor.net.MediaType;

import static com.globalmentor.java.Classes.*;

/**
 * A abstract transferable that carries one or more Java objects. A subclass must implement {@link #transfer(Class)}.
 * @param  The source of the transfer.
 * @author Garret Wilson
 */
public abstract class AbstractObjectTransferable implements Transferable {

	//TODO del	private final Map> contentTypeObjectMap=new HashMap>();

	/** The class representing the type of object to be transferred. */
	//TODO del	private final Class objectClass;

	/** @return The class representing the type of object to be transferred. */
	//TODO del		public Class getObjectClass() {return objectClass;}

	/** The source of the transferable data. */
	private final S source;

	@Override
	public S getSource() {
		return source;
	}

	/** The classes supported by this transferable. */
	private final Class[] objectClasses;

	/** The content types supported by this transferable. */
	private final MediaType[] contentTypes;

	/**
	 * Source and object esclass constructor.
	 * @param source The source of the transferable data.
	 * @param objectClasses The classes indicating the typees of object to be transferred.
	 * @throws NullPointerException if the provided source and/or object classes is null.
	 */
	public AbstractObjectTransferable(final S source, final Class... objectClasses) {
		this.source = requireNonNull(source, "Source cannot be null.");
		this.objectClasses = requireNonNull(objectClasses, "Object classes cannot be null.");
		final int objectClassCount = objectClasses.length; //find out how many object classes there are
		contentTypes = new MediaType[objectClassCount]; //create an array of content types
		for(int i = objectClassCount - 1; i >= 0; --i) { //for each object class
			contentTypes[i] = getObjectMediaType(objectClasses[i]); //create a content type for this object
		}
	}

	/**
	 * Determines the class this content type matches. This method matches a content type against the {@value MediaType#APPLICATION_PRIMARY_TYPE} primary type
	 * and {@value MediaType#X_JAVA_OBJECT} subtype, with a "class" parameter indicating the given object class.
	 * @param contentType The type of data requested, which may include wildcards.
	 * @return The matching class, or null if no supported class matches the requested content type.
	 */
	protected Class getClass(final MediaType contentType) {
		if(contentType.matches(MediaType.APPLICATION_PRIMARY_TYPE, MediaType.X_JAVA_OBJECT)) { //if this is an application/x-java-object type
			final String className = contentType.getParameter("class"); //get the class parameter TODO use a constant
			if(className != null) { //if a class name was given
				for(final Class objectClass : objectClasses) { //for each supported class
					if(objectClass.getName().equals(className)) { //if this class is of the requested type
						return objectClass; //return the match we found
					}
				}
			}
		}
		return null; //indicate that there is no matching class		
	}

	/**
	 * {@inheritDoc}
	 * 
	 * This implementation matches a content type against the {@value MediaType#APPLICATION_PRIMARY_TYPE} primary type and {@value MediaType#X_JAVA_OBJECT}
	 * subtype, with a "class" parameter indicating the given object class.
	 * 
	 */
	@Override
	public boolean canTransfer(final MediaType contentType) {
		return getClass(contentType) != null; //see if there is a class that matches
	}

	/**
	 * {@inheritDoc}
	 * 
	 * This implementation delegates to {@link #transfer(Class)}.
	 * 
	 */
	@Override
	public Object transfer(final MediaType contentType) {
		final Class objectClass = getClass(contentType); //return the class indicated by this content type
		if(objectClass != null) { //if there is a class for this content type
			return transfer(objectClass); //transfer based upon the class
		} else { //if there is no class for this content type
			throw new IllegalArgumentException("Content type not supported: " + contentType);
		}
	}

	/**
	 * {@inheritDoc}
	 * 
	 * This implementation returns content types in the form application/x-java-object;class=package.Class.
	 * 
	 */
	@Override
	public MediaType[] getContentTypes() {
		return contentTypes; //return the available content types
	}
}