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

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Here is the source code for se.kb.oai.ore.impl.AtomSerializer.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 java.util.UUID;

import org.dom4j.DocumentHelper;
import org.dom4j.Element;

import se.kb.oai.ore.AggregatedResource;
import se.kb.oai.ore.Metadata;
import se.kb.oai.ore.ResourceMap;
import se.kb.oai.ore.Type;

import static se.kb.oai.ore.impl.AtomConstants.*;

/**
 * The <code>AtomSerializer</code> class implements the {@link se.kb.oai.ore.ResourceMapSerializer} 
 * interface to provide the functionality of serializing <code>ResourceMap</code> objects into
 * Atom feeds.
 * 
 * @author Oskar Grenholm, National Library of Sweden
 */
public class AtomSerializer extends SerializerBase {

    @Override
    public Element serializeToXml(ResourceMap map) {
        Element feed = DocumentHelper.createElement(FEED);
        feed.addNamespace(ATOM_NS_PREFIX, ATOM_NS_URI);
        feed.addNamespace(RDF_NS_PREFIX, RDF_NS_URI);
        feed.addNamespace(DC_NS_PREFIX, DC_NS_URI);
        feed.addNamespace(DCTERMS_NS_PREFIX, DCTERMS_NS_URI);

        Element id = DocumentHelper.createElement(ID);
        id.setText(createAtomId());
        feed.add(id);

        Element link = DocumentHelper.createElement(LINK);
        link.addAttribute(REL, "self");
        link.addAttribute("type", "application/atom+xml");
        link.addAttribute(HREF, map.getId().toString());
        feed.add(link);

        Element title = DocumentHelper.createElement(TITLE);
        title.setText("Resource Map " + map.getId().toString());
        feed.add(title);

        Element author = DocumentHelper.createElement(AUTHOR);
        Element name = DocumentHelper.createElement(NAME);
        name.setText(map.getCreator());
        author.add(name);
        feed.add(author);

        if (map.getRights() != null) {
            Element rights = DocumentHelper.createElement(RIGHTS);
            rights.setText(map.getRights());
            feed.add(rights);
        }

        if (map.getCreated() != null) {
            Element published = DocumentHelper.createElement(PUBLISHED);
            published.setText(DATE_FORMAT.format(map.getCreated()));
            feed.add(published);
        }

        Element updated = DocumentHelper.createElement(UPDATED);
        updated.setText(DATE_FORMAT.format(map.getModified()));
        feed.add(updated);

        Element category = DocumentHelper.createElement(CATEGORY);
        category.addAttribute(SCHEME, ORE_TERMS_URL);
        category.addAttribute(TERM, ORE_TERMS_REM_URL);
        category.addAttribute(LABEL, "Resource Map");
        feed.add(category);

        Element icon = DocumentHelper.createElement(ICON);
        icon.setText(ICON_URL);
        feed.add(icon);

        link = DocumentHelper.createElement(LINK);
        link.addAttribute(REL, "describes");
        link.addAttribute(HREF, map.getAggregation().getId().toString());
        feed.add(link);

        addTypes(feed, map.getAggregation().getTypes());
        addMetadata(feed, map.getAggregation().getMetadata());

        for (AggregatedResource resource : map.getAggregation().getResources()) {
            Element entry = DocumentHelper.createElement(ENTRY);

            id = DocumentHelper.createElement(ID);
            id.setText(createAtomId());
            entry.add(id);

            title = DocumentHelper.createElement(TITLE);
            title.setText("Aggregated Resource " + resource.getId().toString());
            entry.add(title);

            updated = DocumentHelper.createElement(UPDATED);
            updated.setText(DATE_FORMAT.format(map.getModified()));
            entry.add(updated);

            link = DocumentHelper.createElement(LINK);
            link.addAttribute(REL, "alternate");
            if (resource.getMimeType() != null)
                link.addAttribute(MIME_TYPE, resource.getMimeType());
            link.addAttribute(HREF, resource.getId().toString());
            entry.add(link);

            addTypes(entry, resource.getTypes());
            addMetadata(entry, resource.getMetadata());

            feed.add(entry);
        }

        return feed;
    }

    private void addTypes(Element target, List<Type> list) {
        for (Type type : list) {
            Element element = DocumentHelper.createElement(TYPE);
            element.setText(type.getValue());
            target.add(element);
        }
    }

    private void addMetadata(Element target, List<Metadata> list) {
        for (Metadata metadata : list) {
            Element element = DocumentHelper.createElement(metadata.getName());
            element.setText(metadata.getValue());
            target.add(element);
        }
    }

    protected String createAtomId() {
        return "urn:uuid:" + UUID.randomUUID().toString();
    }
}