org.entrystore.repository.impl.converters.OAI_DC2RDFGraphConverter.java Source code

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Here is the source code for org.entrystore.repository.impl.converters.OAI_DC2RDFGraphConverter.java

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/*
 * Copyright (c) 2007-2014 MetaSolutions AB
 *
 * 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 org.entrystore.repository.impl.converters;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.entrystore.repository.Converter;
import org.openrdf.model.Graph;
import org.openrdf.model.Literal;
import org.openrdf.model.ValueFactory;
import org.openrdf.model.impl.GraphImpl;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class OAI_DC2RDFGraphConverter implements Converter {

    private static Log log = LogFactory.getLog(OAI_DC2RDFGraphConverter.class);

    Map<String, Locale> localeMap;

    static {
        String[] languages = Locale.getISOLanguages();
        Map<String, Locale> localeMap = new HashMap<String, Locale>(languages.length);
        for (String language : languages) {
            Locale locale = new Locale(language);
            localeMap.put(locale.getISO3Language(), locale);
        }
    }

    /**
     * Converts an oai_dc xml document tag metadata to a graph.
     * 
     * @param from
     *            An XML NodeList.
     * 
     * @param resourceURI
     *            Root URI of the resource's metadata.
     * 
     * @return the new metadata graph.
     */
    public Object convert(Object from, java.net.URI resourceURI, java.net.URI metadataURI) {
        NodeList metadataList = null;

        if (from instanceof NodeList) {
            metadataList = (NodeList) from;
        } else if (from instanceof Node) {
            metadataList = ((Node) from).getChildNodes();
        } else {
            log.warn("Unable to convert object, class type not supported");
            return null;
        }

        Graph graph = new GraphImpl();
        ValueFactory vf = graph.getValueFactory();
        org.openrdf.model.URI root = vf.createURI(resourceURI.toString());

        for (int i = 0; i < metadataList.getLength(); i++) {
            Node n = metadataList.item(i);
            if (n == null || "#text".equals(n.getNodeName())) {
                continue;
            }

            String nodeNS = n.getNamespaceURI();
            String nodeName = n.getNodeName();
            String predicate = null;
            if (nodeName.contains(":") && (nodeNS != null)) {
                nodeName = nodeName.substring(nodeName.indexOf(":") + 1);
                predicate = nodeNS + nodeName;
            } else {
                predicate = nodeName;
            }
            String nodeContent = n.getTextContent();
            if (nodeContent == null) {
                continue;
            }
            nodeContent = nodeContent.trim();

            // fix to create a valid language literal with a 2-letter ISO code
            // this is about the language value as a literal, attributes are treated further down
            if ("language".equalsIgnoreCase(nodeName)) {
                // convert 3-letter to 2-letter ISO code
                if (nodeContent.length() == 3) {
                    nodeContent = getISO2Language(nodeContent);
                }
            }
            // <- fix

            // fix to convert ISO 3-letter lang codes to 2-letter codes
            // this is about LangStrings in general
            NamedNodeMap nodeAttributes = n.getAttributes();
            String lang = null;
            if (nodeAttributes != null) {
                Node langNode = nodeAttributes.getNamedItem("xml:lang");
                if (langNode != null) {
                    lang = langNode.getNodeValue();
                    if (lang != null) {
                        lang = lang.trim();
                        if (lang.length() == 3) {
                            lang = getISO2Language(lang.toLowerCase());
                        }
                    }
                }
            }
            // <- fix

            Literal lit;
            if (lang != null) {
                lit = vf.createLiteral(nodeContent, lang);
            } else {
                lit = vf.createLiteral(nodeContent);
            }

            graph.add(root, new org.openrdf.model.impl.URIImpl(predicate), lit);
        }

        return graph;
    }

    private String getISO2Language(String iso3Language) {
        if (localeMap == null) {
            String[] languages = Locale.getISOLanguages();
            localeMap = new HashMap<String, Locale>(languages.length);
            for (String language : languages) {
                Locale locale = new Locale(language);
                localeMap.put(locale.getISO3Language(), locale);
            }
        }
        Locale locale = localeMap.get(iso3Language);
        if (locale != null) {
            return locale.getLanguage();
        }
        return null;
    }

}