qdccrosswalk.java

dspace 用j2ee架构的一个数字图书馆.开源程序

/*
 * QDCCrosswalk.java
 *
 * Version: $Revision: 1.2 $
 *
 * Date: $Date: 2006/03/17 00:04:38 $
 *
 * Copyright (c) 2002-2005, Hewlett-Packard Company and Massachusetts
 * Institute of Technology.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Hewlett-Packard Company nor the name of the
 * Massachusetts Institute of Technology nor the names of their
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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 */

package org.dspace.content.crosswalk;

import java.io.IOException;
import java.sql.SQLException;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Properties;
import java.util.Enumeration;
import java.io.StringReader;
import java.io.File;
import java.io.FileInputStream;

import java.sql.SQLException;

import org.apache.log4j.Logger;

import org.dspace.core.Context;
import org.dspace.core.Constants;
import org.dspace.content.Item;
import org.dspace.content.DCValue;
import org.dspace.content.DSpaceObject;
import org.dspace.content.MetadataSchema;
import org.dspace.authorize.AuthorizeException;
import org.dspace.core.ConfigurationManager;
import org.dspace.core.SelfNamedPlugin;

import org.jdom.*;
import org.jdom.output.XMLOutputter;
import org.jdom.output.Format;
import org.jdom.input.SAXBuilder;
import org.jdom.input.JDOMParseException;

/**
 * Configurable QDC Crosswalk
 * <p>
 * This class supports multiple dissemination crosswalks from DSpace
 * internal data to the Qualified Dublin Core XML format
 *  (see <a href="http://dublincore.org/">http://dublincore.org/</a>
 * <p>
 * It registers multiple Plugin names, which it reads from
 * the DSpace configuration as follows:
 *
 * <h3>Configuration</h3>
 * Every key starting with <code>"crosswalk.qdc.properties."</code> describes a
 * QDC crosswalk.  Everything after the last period is the <em>plugin instance</em>,
 * and the value is the pathname (relative to <code><em>dspace.dir</em>/config</code>)
 * of the crosswalk configuration file.
 * <p>
 * You can have two aliases point to the same crosswalk,
 * just add two configuration entries with the same value, e.g.
 * <pre>
 *    crosswalk.qdc.properties.QDC = xwalk/qdc.properties
 *    crosswalk.qdc.properties.default = xwalk/qdc.properties
 * </pre>
 * The first line creates a plugin with the name <code>"QDC"</code>
 * which is configured from the file <em>dspace-dir</em><code>/xwalk/qdc.properties</code>.
 * <p>
 * Since there is significant overhead in reading the properties file to
 * configure the crosswalk, and a crosswalk instance may be used any number
 * of times, we recommend caching one instance of the crosswalk for each
 * alias and simply reusing those instances. The PluginManager does
 * this by default.
 * <p>
 * Each named crosswalk has two other types of configuration lines:
 * <p>
 * XML Namespaces: all XML namespace prefixes used in the XML fragments below
 * <em>must</em> be defined in the configuration as follows.  Add a line of
 * the form: <pre>
 *  crosswalk.qdc.namespace.{NAME}.{prefix} = {namespace-URI}</pre>
 * e.g. for the namespaces <code>dc</code> and <code>dcterms</code>
 * in the plugin named <code>QDC</code>, add these lines:
 * <pre>crosswalk.qdc.namespace.QDC.dc = http://purl.org/dc/elements/1.1/
 * crosswalk.qdc.namespace.QDC.dcterms = http://purl.org/dc/terms/</pre>
 *
 * <p>
 * Finally, you need to declare an XML Schema URI for the plugin, with
 * a line of the form <pre>
 *  crosswalk.qdc.schema.{NAME} = {schema-URI}</pre>
 * for example,
 * <pre>crosswalk.qdc.schemaLocation.QDC  = \
 *  http://purl.org/dc/terms/ \
 *  http://dublincore.org/schemas/xmls/qdc/2003/04/02/qualifieddc.xsd</pre>
 *
 * @author Larry Stone
 * @version $Revision: 1.2 $
 */
public class QDCCrosswalk extends SelfNamedPlugin
    implements DisseminationCrosswalk, IngestionCrosswalk
{
    /** log4j category */
    private static Logger log = Logger.getLogger(QDCCrosswalk.class);

    // map of qdc to JDOM Element
    private HashMap qdc2element = new HashMap();

    // map of JDOM Element to qdc DCValue
    private HashMap element2qdc = new HashMap();

    // the XML namespaces from config file for this name.
    private Namespace namespaces[] = null;

    private static final Namespace DCTERMS_NS =
        Namespace.getNamespace("dcterms", "http://purl.org/dc/terms/");

    // sentinal: done init?
    private boolean inited = false;

    // my plugin name
    private String myName = null;

    // prefix of all DSpace Configuration entries.
    private static final String CONFIG_PREFIX = "crosswalk.qdc";

    // XML schemaLocation fragment for this crosswalk, from config.
    private String schemaLocation = null;

    private static final Namespace XLINK_NS =
        Namespace.getNamespace("xlink", "http://www.w3.org/TR/xlink");

    private static XMLOutputter outputUgly = new XMLOutputter();
    private static XMLOutputter outputPretty = new XMLOutputter(Format.getPrettyFormat());
    private static SAXBuilder builder = new SAXBuilder();

    /**
     * Fill in the plugin-name table from DSpace configuration entries
     * for configuration files for flavors of QDC crosswalk:
     */
    private static String aliases[] = null;
    static
    {
        List aliasList = new ArrayList();
        Enumeration pe = ConfigurationManager.propertyNames();
        String propname = CONFIG_PREFIX + ".properties.";
        while (pe.hasMoreElements())
        {
            String key = (String)pe.nextElement();
            if (key.startsWith(propname))
                aliasList.add(key.substring(propname.length()));
        }
        aliases = (String[])aliasList.toArray(new String[aliasList.size()]);
    }

    public static String[] getPluginNames()
    {
        return aliases;
    }

    // utility: return "fully qualified" name of XML element, for a
    // hashtable key to use on ingesting elements.
    // Format is {prefix:}name  where prefix is optional.
    private String makeQualifiedTagName(Element element)
    {
        String prefix = "";
        Namespace ns = element.getNamespace();
        if (ns != null)
            prefix = ns.getPrefix() + ":";
        return prefix+element.getName();
    }

    /**
     * Initialize Crosswalk table from a properties file
     * which itself is the value of the DSpace configuration property
     * "crosswalk.qdc.properties.X", where "X" is the alias name of this instance.
     * Each instance may be configured with a separate mapping table.
     *
     * The QDC crosswalk configuration properties follow the format:
     *
     *  {qdc-element} = {XML-fragment}
     *
     *  1. qualified DC field name is of the form (qualifier is optional)
     *       {MDschema}.{element}.{qualifier}
     *
     *      e.g.  dc.contributor.author
     *            dc.title
     *
     *  2. XML fragment is prototype of metadata element, with empty
     *     placeholders for value).
     *
     * Example properties line: