se.kb.oai.ore.impl.AtomFactory.java Source code

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Here is the source code for se.kb.oai.ore.impl.AtomFactory.java

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/*
 * Copyright 2008 National Library of Sweden 
 * 
 * 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 se.kb.oai.ore.impl;

import java.util.List;

import org.dom4j.Element;
import org.dom4j.Node;

import se.kb.oai.OAIException;
import se.kb.oai.ore.AggregateBase;
import se.kb.oai.ore.AggregatedResource;
import se.kb.oai.ore.Metadata;
import se.kb.oai.ore.Metadata.Namespace;
import se.kb.oai.ore.ResourceMap;
import se.kb.oai.ore.Type;
import se.kb.xml.XPathWrapper;

import static se.kb.oai.ore.OREConstants.ATOM_NS_PREFIX;
import static se.kb.oai.ore.OREConstants.ATOM_NS_URI;
import static se.kb.oai.ore.OREConstants.DCTERMS_NS_PREFIX;
import static se.kb.oai.ore.OREConstants.DCTERMS_NS_URI;
import static se.kb.oai.ore.OREConstants.DC_NS_PREFIX;
import static se.kb.oai.ore.OREConstants.DC_NS_URI;
import static se.kb.oai.ore.OREConstants.RDF_NS_PREFIX;
import static se.kb.oai.ore.OREConstants.RDF_NS_URI;
import static se.kb.oai.ore.impl.AtomConstants.*;

/**
 * The <code>AtomFactory</code> class implements the {@link se.kb.oai.ore.ResourceMapFactory} 
 * interface to provide the functionality to parse Atom feeds and turn them into
 * <code>ResourceMap</code> objects.
 * 
 * @author Oskar Grenholm, National Library of Sweden
 */
public class AtomFactory extends FactoryBase {

    @Override
    public ResourceMap getResourceMap(Element feed) throws OAIException {
        try {
            XPathWrapper xpath = createXPath(feed);

            ResourceMap map = new ResourceMap(xpath.valueOf(ID_XPATH));
            map.setCreator(xpath.valueOf(CREATOR_XPATH));
            map.setModified(DATE_FORMAT.parse(xpath.valueOf(MODIFIED_XPATH)));

            String rights = xpath.valueOf(RIGHTS_XPATH);
            if (notEmpty(rights))
                map.setRights(rights);

            String created = xpath.valueOf(CREATED_XPATH);
            if (notEmpty(created))
                map.setCreated(DATE_FORMAT.parse(created));

            addTypesAndMetadata(map.getAggregation(), xpath.selectNodes("*"));

            for (Node node : xpath.selectNodes(ENTRY_XPATH)) {
                xpath = createXPath(node);
                AggregatedResource resource = new AggregatedResource(xpath.valueOf(ENTRY_ID_XPATH));
                addTypesAndMetadata(resource, xpath.selectNodes("*"));
                map.getAggregation().addResource(resource);
            }

            return map;
        } catch (Exception e) {
            throw new OAIException(e);
        }
    }

    private void addTypesAndMetadata(AggregateBase aggregate, List<Node> nodes) {
        for (Node node : nodes) {
            Element element = (Element) node;
            if (element.getNamespace().equals(DC_NS)) {
                aggregate.addMetadata((new Metadata(Namespace.DC, element.getName(), element.getText())));
            } else if (element.getNamespace().equals(DCTERMS_NS)) {
                aggregate.addMetadata((new Metadata(Namespace.DCTERMS, element.getName(), element.getText())));
            } else if (element.getNamespace().equals(RDF_NS) && element.getName().equals("type")) {
                aggregate.addType(new Type(element.getText()));
            }
        }
    }

    private XPathWrapper createXPath(Node node) {
        XPathWrapper xpath = new XPathWrapper(node);
        xpath.addNamespace(ATOM_NS_PREFIX, ATOM_NS_URI);
        xpath.addNamespace(RDF_NS_PREFIX, RDF_NS_URI);
        xpath.addNamespace(DC_NS_PREFIX, DC_NS_URI);
        xpath.addNamespace(DCTERMS_NS_PREFIX, DCTERMS_NS_URI);
        return xpath;
    }

    private boolean notEmpty(String string) {
        return (string != null && string.trim().length() > 0);
    }
}