JDOMQueryUtil.java

/**
 * Copyright 2008 The University of North Carolina at Chapel Hill
 *
 * 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 edu.unc.lib.dl.xml;

import java.text.ParseException;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.jdom2.Element;
import org.jdom2.Namespace;

import edu.unc.lib.dl.fedora.PID;
import edu.unc.lib.dl.util.ContentModelHelper.Relationship;
import edu.unc.lib.dl.util.DateTimeUtil;

public class JDOMQueryUtil {

	public static Element getElementByAttribute(List<?> elements, String attribute, String value) {
		return getElementByAttribute(elements, attribute, null, value);
	}

	public static Element getElementByAttribute(List<?> elements, String attribute, Namespace attributeNS, String value) {
		for (Object elementObj : elements) {
			Element element = (Element) elementObj;
			String attrValue = attributeNS == null ? element.getAttributeValue(attribute) : element.getAttributeValue(attribute, attributeNS);
			if (attrValue == value || (value != null && value.equals(attrValue))) {
				return element;
			}
		}
		return null;
	}

	public static Element getChildByAttribute(Element parent, String childName, Namespace namespace, String attribute, String value) {
		List<?> elements;
		if (childName != null) {
			if (namespace != null)
				elements = parent.getChildren(childName, namespace);
			else elements = parent.getChildren(childName);
		} else {
			elements = parent.getChildren();
		}
		return getElementByAttribute(elements, attribute, value);
	}

	public static Date parseISO6392bDateChild(Element parent, String childName, Namespace namespace) {
		String dateString = parent.getChildText(childName, namespace);
		if (dateString != null) {
			try {
				return DateTimeUtil.parseUTCToDate(dateString);
			} catch (ParseException e) {
				// Wasn't a valid date, ignore it.
			} catch (IllegalArgumentException e) {
				// Wasn't a valid date, ignore it.
			}
		}
		return null;
	}

	/**
	 * Returns a set of object PIDs retrieved from the provided RDF datastream
	 *
	 * @param rdfRoot
	 * @param relation
	 * @return
	 */
	public static Set<PID> getRelationSet(Element rdfRoot, Relationship relation) {
		List<Element> containsEls = rdfRoot.getChild("Description", JDOMNamespaceUtil.RDF_NS).getChildren(
				relation.name(), relation.getNamespace());
		Set<PID> children = new HashSet<>();
		for (Element containsEl : containsEls) {
			children.add(new PID(containsEl.getAttributeValue("resource", JDOMNamespaceUtil.RDF_NS)));
		}
		return children;
	}
}