to.networld.android.divedroid.model.rdf.RDFParser.java Source code

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Here is the source code for to.networld.android.divedroid.model.rdf.RDFParser.java

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/**
 * DiveDroid
 *
 * Copyright (C) 2010-2011 by Networld Project
 * Written by Alex Oberhauser <oberhauseralex@networld.to>
 * All Rights Reserved
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation, version 3 of the License.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this software.  If not, see <http://www.gnu.org/licenses/>
 */

package to.networld.android.divedroid.model.rdf;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Vector;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.QName;
import org.dom4j.io.SAXReader;
import org.jaxen.JaxenException;
import org.jaxen.SimpleNamespaceContext;
import org.jaxen.XPath;
import org.jaxen.dom4j.Dom4jXPath;

/**
 * Superclass that hiddes the low level RDF parsing code. Each class that needs to parse
 * RDF files should extend this class.
 * 
 * @author Alex Oberhauser
 *
 */
public class RDFParser {
    protected final SAXReader reader;
    protected Document document;
    protected HashMap<String, String> namespace = new HashMap<String, String>();
    protected String queryPrefix = "/";

    public RDFParser() {
        this.reader = new SAXReader();
        this.initDefaultNamespace();
    }

    protected void initDefaultNamespace() {
        this.namespace.put("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
        this.namespace.put("rdfs", "http://www.w3.org/2000/01/rdf-schema#");
    }

    @SuppressWarnings("unchecked")
    protected List<Element> getLinkNodes(String _query) {
        try {
            XPath xpath = new Dom4jXPath(_query);
            xpath.setNamespaceContext(new SimpleNamespaceContext(this.namespace));
            return (List<Element>) xpath.selectNodes(this.document);
        } catch (JaxenException e) {
            e.printStackTrace();
            return new LinkedList<Element>();
        }
    }

    @SuppressWarnings("unchecked")
    protected String getResourceLinkNodes(String _query, String _resource) {
        try {
            XPath xpath = new Dom4jXPath(_query);
            xpath.setNamespaceContext(new SimpleNamespaceContext(this.namespace));
            List<Element> elements = (List<Element>) xpath.selectNodes(this.document);
            if (elements.size() > 0)
                return elements.get(0).attributeValue(
                        new QName("resource", new Namespace("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#")));
        } catch (JaxenException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * Please set before you call the function the variables this.namespace and this.queryPrefix.
     * 
     * @param _nodeName The name of the node for example 'dive:name'
     * @return
     */
    protected String getSingleNode(String _nodeName) {
        List<Element> nodeList = this.getLinkNodes(this.queryPrefix + "/" + _nodeName);
        if (nodeList.size() > 0)
            return nodeList.get(0).getTextTrim();
        else
            return null;
    }

    protected Vector<String> getResourceNodes(String _nodeName, String _resourceName) {
        List<Element> resourceList = this.getLinkNodes(this.queryPrefix + "/" + _nodeName);
        Vector<String> retVector = new Vector<String>();
        for (Element entry : resourceList) {
            retVector.add(entry.valueOf("@" + _resourceName));
        }
        return retVector;
    }

    /**
     * Please set before you call the function the variables this.namespace and this.queryPrefix.
     * 
     * @param _nodeName The name of the node for example 'dive:name'
     * @return
     */
    protected String getSingleResourceNode(String _nodeName, String _resourceName) {
        List<Element> nodeList = this.getLinkNodes(this.queryPrefix + "/" + _nodeName);
        if (nodeList.size() > 0)
            return nodeList.get(0).valueOf("@" + _resourceName);
        else
            return null;
    }
}