GenericCollectionElementExporter.java

/*
 * This is a common dao with basic CRUD operations and is not limited to any
 * persistent layer implementation
 *
 * Copyright (C) 2009 Imran M Yousuf (imyousuf@smartitengineering.com)
 *
 * 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 3 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
 */
package com.smartitengineering.exim.impl.xml;

import com.smartitengineering.exim.AssociationConfig.AssociationType;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import javax.xml.transform.sax.TransformerHandler;
import org.xml.sax.helpers.AttributesImpl;

/**
 * Implements element exporter for all non-map collection types, i.e.
 * {@link List}, {@link Set}, {@link Collection} and array.
 * @author imyousuf
 * @since 0.4
 */
public class GenericCollectionElementExporter
				extends AbstractElementExporter
				implements ElementExporter {

		private static ElementExporter exporter;

		static {
				exporter = new GenericCollectionElementExporter();
				for (AssociationType type : exporter.getSupportedTypes()) {
						XMLExporterImpl.addHandler(type, exporter);
				}
		}

		public static ElementExporter getInstance() {
				return exporter;
		}

		public GenericCollectionElementExporter() {
				Collections.addAll(types, AssociationType.TYPE_ARRAY,
								AssociationType.TYPE_COLLECTION, AssociationType.TYPE_LIST,
								AssociationType.TYPE_SET);
		}

		public void exportElement(AssociationType type,
															Object object,
															TransformerHandler handler)
						throws IOException {
				if (type == null || object == null || handler == null) {
						throw new IOException("All parameters are required!");
				}
				try {
						AttributesImpl atts = new AttributesImpl();
						handler.startElement(EXIM_COLLECN_URI, EXIM_COLLECTION_NS, type.
										getSimpleName(), atts);
						Collection objects;
						switch (type) {
								case TYPE_ARRAY:
										objects = Arrays.asList((Object[]) object);
										break;
								case TYPE_LIST:
								case TYPE_SET:
								case TYPE_COLLECTION:
										objects = (Collection) object;
										break;
								default:
										throw new IOException("Unsupported type - " + type);
						}
						for (Object exportObj : objects) {
								handler.startElement("", "", "item",
												atts);
								AssociationType associationType = AssociationType.
												getAssociationType(exportObj.getClass());
								XMLExporterImpl.getElementExporter(associationType).
												exportElement(associationType, exportObj, handler);
								handler.endElement("", "", "item");
						}
						handler.endElement(EXIM_COLLECN_URI, EXIM_COLLECTION_NS, type.
										getSimpleName());
				}
				catch (Exception ex) {
						throw new IOException(ex);
				}
		}
}