Java tutorial
/** * The contents of this file are subject to the license and copyright * detailed in the LICENSE and NOTICE files at the root of the source * tree and available online at * * http://www.dspace.org/license/ */ package org.dspace.content.crosswalk; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.StringReader; import java.sql.SQLException; import java.util.ArrayList; import java.util.Enumeration; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Properties; import org.apache.commons.lang.ArrayUtils; import org.apache.log4j.Logger; import org.dspace.authorize.AuthorizeException; import org.dspace.content.DCValue; import org.dspace.content.DSpaceObject; import org.dspace.content.Collection; import org.dspace.content.Community; import org.dspace.content.Item; import org.dspace.content.Site; import org.dspace.core.ConfigurationManager; import org.dspace.core.Constants; import org.dspace.core.SelfNamedPlugin; import org.jdom.Attribute; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.Namespace; import org.jdom.Text; import org.jdom.Verifier; import org.jdom.input.SAXBuilder; import org.jdom.output.XMLOutputter; import org.jdom.xpath.XPath; /** * Configurable MODS Crosswalk * <p> * This class supports multiple dissemination crosswalks from DSpace * internal data to the MODS XML format * (see <a href="http://www.loc.gov/standards/mods/">http://www.loc.gov/standards/mods/</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.mods.properties."</code> describes a * MODS crosswalk. Everything after the last period is the <em>plugin name</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 names point to the same crosswalk, * just add two configuration entries with the same value, e.g. * <pre> * crosswalk.mods.properties.MODS = crosswalks/mods.properties * crosswalk.mods.properties.default = crosswalks/mods.properties * </pre> * The first line creates a plugin with the name <code>"MODS"</code> * which is configured from the file <em>dspace-dir</em><code>/config/crosswalks/mods.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 * name and simply reusing those instances. The PluginManager does this * by default. * * @author Larry Stone * @author Scott Phillips * @version $Revision$ */ public class MODSDisseminationCrosswalk extends SelfNamedPlugin implements DisseminationCrosswalk { /** log4j category */ private static Logger log = Logger.getLogger(MODSDisseminationCrosswalk.class); private static final String CONFIG_PREFIX = "crosswalk.mods.properties."; /** * Fill in the plugin alias table from DSpace configuration entries * for configuration files for flavors of MODS crosswalk: */ private static String aliases[] = null; static { List<String> aliasList = new ArrayList<String>(); Enumeration<String> pe = (Enumeration<String>) ConfigurationManager.propertyNames(); while (pe.hasMoreElements()) { String key = pe.nextElement(); if (key.startsWith(CONFIG_PREFIX)) { aliasList.add(key.substring(CONFIG_PREFIX.length())); } } aliases = (String[]) aliasList.toArray(new String[aliasList.size()]); } public static String[] getPluginNames() { return (String[]) ArrayUtils.clone(aliases); } /** * MODS namespace. */ public static final Namespace MODS_NS = Namespace.getNamespace("mods", "http://www.loc.gov/mods/v3"); private static final Namespace XLINK_NS = Namespace.getNamespace("xlink", "http://www.w3.org/1999/xlink"); private static final Namespace namespaces[] = { MODS_NS, XLINK_NS }; /** URL of MODS XML Schema */ public static final String MODS_XSD = "http://www.loc.gov/standards/mods/v3/mods-3-1.xsd"; private static final String schemaLocation = MODS_NS.getURI() + " " + MODS_XSD; private static XMLOutputter outputUgly = new XMLOutputter(); private static SAXBuilder builder = new SAXBuilder(); private Map<String, modsTriple> modsMap = null; /** * Container for crosswalk mapping: expressed as "triple" of: * 1. QDC field name (really field.qualifier). * 2. XML subtree to add to MODS record. * 3. XPath expression showing places to plug in the value. */ static class modsTriple { public String qdc = null; public Element xml = null; public XPath xpath = null; /** * Initialize from text versions of QDC, XML and XPath. * The DC stays a string; parse the XML with appropriate * namespaces; "compile" the XPath. */ public static modsTriple create(String qdc, String xml, String xpath) { modsTriple result = new modsTriple(); final String prolog = "<mods xmlns:" + MODS_NS.getPrefix() + "=\"" + MODS_NS.getURI() + "\" " + "xmlns:" + XLINK_NS.getPrefix() + "=\"" + XLINK_NS.getURI() + "\">"; final String postlog = "</mods>"; try { result.qdc = qdc; result.xpath = XPath.newInstance(xpath); result.xpath.addNamespace(MODS_NS.getPrefix(), MODS_NS.getURI()); result.xpath.addNamespace(XLINK_NS); Document d = builder.build(new StringReader(prolog + xml + postlog)); result.xml = (Element) d.getRootElement().getContent(0); } catch (JDOMException je) { log.error("Error initializing modsTriple(\"" + qdc + "\",\"" + xml + "\",\"" + xpath + "\"): got " + je.toString()); return null; } catch (IOException je) { log.error("Error initializing modsTriple(\"" + qdc + "\",\"" + xml + "\",\"" + xpath + "\"): got " + je.toString()); return null; } return result; } } /** * Initialize Crosswalk table from a properties file * which itself is the value of the DSpace configuration property * "crosswalk.mods.properties.X", where "X" is the alias name of this instance. * Each instance may be configured with a separate mapping table. * * The MODS crosswalk configuration properties follow the format: * * {field-name} = {XML-fragment} | {XPath} * * 1. qualified DC field name is of the form * {MDschema}.{element}.{qualifier} * * e.g. dc.contributor.author * * 2. XML fragment is prototype of metadata element, with empty or "%s" * placeholders for value(s). NOTE: Leave the %s's in becaue * it's much easier then to see if something is broken. * * 3. XPath expression listing point(s) in the above XML where * the value is to be inserted. Context is the element itself. * * Example properties line: * * dc.description.abstract = <mods:abstract>%s</mods:abstract> | text() * */ private void initMap() throws CrosswalkInternalException { if (modsMap != null) { return; } String myAlias = getPluginInstanceName(); if (myAlias == null) { log.error( "Must use PluginManager to instantiate MODSDisseminationCrosswalk so the class knows its name."); return; } String cmPropName = CONFIG_PREFIX + myAlias; String propsFilename = ConfigurationManager.getProperty(cmPropName); if (propsFilename == null) { String msg = "MODS crosswalk missing " + "configuration file for crosswalk named \"" + myAlias + "\""; log.error(msg); throw new CrosswalkInternalException(msg); } else { String parent = ConfigurationManager.getProperty("dspace.dir") + File.separator + "config" + File.separator; File propsFile = new File(parent, propsFilename); Properties modsConfig = new Properties(); FileInputStream pfs = null; try { pfs = new FileInputStream(propsFile); modsConfig.load(pfs); } catch (IOException e) { log.error("Error opening or reading MODS properties file: " + propsFile.toString() + ": " + e.toString()); throw new CrosswalkInternalException("MODS crosswalk cannot " + "open config file: " + e.toString(), e); } finally { if (pfs != null) { try { pfs.close(); } catch (IOException ioe) { } } } modsMap = new HashMap<String, modsTriple>(); Enumeration<String> pe = (Enumeration<String>) modsConfig.propertyNames(); while (pe.hasMoreElements()) { String qdc = pe.nextElement(); String val = modsConfig.getProperty(qdc); String pair[] = val.split("\\s+\\|\\s+", 2); if (pair.length < 2) { log.warn("Illegal MODS mapping in " + propsFile.toString() + ", line = " + qdc + " = " + val); } else { modsTriple trip = modsTriple.create(qdc, pair[0], pair[1]); if (trip != null) { modsMap.put(qdc, trip); } } } } } /** * Return the MODS namespace */ public Namespace[] getNamespaces() { return (Namespace[]) ArrayUtils.clone(namespaces); } /** * Return the MODS schema */ public String getSchemaLocation() { return schemaLocation; } /** * Returns object's metadata in MODS format, as List of XML structure nodes. */ public List<Element> disseminateList(DSpaceObject dso) throws CrosswalkException, IOException, SQLException, AuthorizeException { return disseminateListInternal(dso, true); } /** * Disseminate an Item, Collection, or Community to MODS. */ public Element disseminateElement(DSpaceObject dso) throws CrosswalkException, IOException, SQLException, AuthorizeException { Element root = new Element("mods", MODS_NS); root.setAttribute("schemaLocation", schemaLocation, XSI_NS); root.addContent(disseminateListInternal(dso, false)); return root; } private List<Element> disseminateListInternal(DSpaceObject dso, boolean addSchema) throws CrosswalkException, IOException, SQLException, AuthorizeException { DCValue[] dcvs = null; if (dso.getType() == Constants.ITEM) { dcvs = item2Metadata((Item) dso); } else if (dso.getType() == Constants.COLLECTION) { dcvs = collection2Metadata((Collection) dso); } else if (dso.getType() == Constants.COMMUNITY) { dcvs = community2Metadata((Community) dso); } else if (dso.getType() == Constants.SITE) { dcvs = site2Metadata((Site) dso); } else { throw new CrosswalkObjectNotSupported( "MODSDisseminationCrosswalk can only crosswalk Items, Collections, or Communities"); } initMap(); List<Element> result = new ArrayList<Element>(dcvs.length); for (int i = 0; i < dcvs.length; i++) { String qdc = dcvs[i].schema + "." + dcvs[i].element; if (dcvs[i].qualifier != null) { qdc += "." + dcvs[i].qualifier; } String value = dcvs[i].value; modsTriple trip = modsMap.get(qdc); if (trip == null) { log.warn("WARNING: " + getPluginInstanceName() + ": No MODS mapping for \"" + qdc + "\""); } else { try { Element me = (Element) trip.xml.clone(); if (addSchema) { me.setAttribute("schemaLocation", schemaLocation, XSI_NS); } Iterator ni = trip.xpath.selectNodes(me).iterator(); if (!ni.hasNext()) { log.warn("XPath \"" + trip.xpath.getXPath() + "\" found no elements in \"" + outputUgly.outputString(me) + "\", qdc=" + qdc); } while (ni.hasNext()) { Object what = ni.next(); if (what instanceof Element) { ((Element) what).setText(checkedString(value)); } else if (what instanceof Attribute) { ((Attribute) what).setValue(checkedString(value)); } else if (what instanceof Text) { ((Text) what).setText(checkedString(value)); } else { log.warn("Got unknown object from XPath, class=" + what.getClass().getName()); } } result.add(me); } catch (JDOMException je) { log.error("Error following XPath in modsTriple: context=" + outputUgly.outputString(trip.xml) + ", xpath=" + trip.xpath.getXPath() + ", exception=" + je.toString()); } } } return result; } /** * ModsCrosswalk can disseminate: Items, Collections, Communities, and Site. */ public boolean canDisseminate(DSpaceObject dso) { return (dso.getType() == Constants.ITEM || dso.getType() == Constants.COLLECTION || dso.getType() == Constants.COMMUNITY || dso.getType() == Constants.SITE); } /** * ModsCrosswalk prefer's element form over list. */ public boolean preferList() { return false; } /** * Generate a list of metadata elements for the given DSpace * site. * * @param site * The site to derive metadata from */ protected DCValue[] site2Metadata(Site site) { List<DCValue> metadata = new ArrayList<DCValue>(); String identifier_uri = "http://hdl.handle.net/" + site.getHandle(); String title = site.getName(); String url = site.getURL(); if (identifier_uri != null) { metadata.add(createDCValue("identifier.uri", null, identifier_uri)); } //FIXME: adding two URIs for now (site handle and URL), in case site isn't using handles if (url != null) { metadata.add(createDCValue("identifier.uri", null, url)); } if (title != null) { metadata.add(createDCValue("title", null, title)); } return (DCValue[]) metadata.toArray(new DCValue[metadata.size()]); } /** * Generate a list of metadata elements for the given DSpace * community. * * @param community * The community to derive metadata from */ protected DCValue[] community2Metadata(Community community) { List<DCValue> metadata = new ArrayList<DCValue>(); String description = community.getMetadata("introductory_text"); String description_abstract = community.getMetadata("short_description"); String description_table = community.getMetadata("side_bar_text"); String identifier_uri = "http://hdl.handle.net/" + community.getHandle(); String rights = community.getMetadata("copyright_text"); String title = community.getMetadata("name"); if (description != null) { metadata.add(createDCValue("description", null, description)); } if (description_abstract != null) { metadata.add(createDCValue("description", "abstract", description_abstract)); } if (description_table != null) { metadata.add(createDCValue("description", "tableofcontents", description_table)); } if (identifier_uri != null) { metadata.add(createDCValue("identifier.uri", null, identifier_uri)); } if (rights != null) { metadata.add(createDCValue("rights", null, rights)); } if (title != null) { metadata.add(createDCValue("title", null, title)); } return (DCValue[]) metadata.toArray(new DCValue[metadata.size()]); } /** * Generate a list of metadata elements for the given DSpace * collection. * * @param collection * The collection to derive metadata from */ protected DCValue[] collection2Metadata(Collection collection) { List<DCValue> metadata = new ArrayList<DCValue>(); String description = collection.getMetadata("introductory_text"); String description_abstract = collection.getMetadata("short_description"); String description_table = collection.getMetadata("side_bar_text"); String identifier_uri = "http://hdl.handle.net/" + collection.getHandle(); String provenance = collection.getMetadata("provenance_description"); String rights = collection.getMetadata("copyright_text"); String rights_license = collection.getMetadata("license"); String title = collection.getMetadata("name"); if (description != null) { metadata.add(createDCValue("description", null, description)); } if (description_abstract != null) { metadata.add(createDCValue("description", "abstract", description_abstract)); } if (description_table != null) { metadata.add(createDCValue("description", "tableofcontents", description_table)); } if (identifier_uri != null) { metadata.add(createDCValue("identifier", "uri", identifier_uri)); } if (provenance != null) { metadata.add(createDCValue("provenance", null, provenance)); } if (rights != null) { metadata.add(createDCValue("rights", null, rights)); } if (rights_license != null) { metadata.add(createDCValue("rights.license", null, rights_license)); } if (title != null) { metadata.add(createDCValue("title", null, title)); } return (DCValue[]) metadata.toArray(new DCValue[metadata.size()]); } /** * Generate a list of metadata elements for the given DSpace item. * * @param item * The item to derive metadata from */ protected DCValue[] item2Metadata(Item item) { DCValue[] dcvs = item.getMetadata(Item.ANY, Item.ANY, Item.ANY, Item.ANY); return dcvs; } private DCValue createDCValue(String element, String qualifier, String value) { DCValue dcv = new DCValue(); dcv.schema = "dc"; dcv.element = element; dcv.qualifier = qualifier; dcv.value = value; return dcv; } // check for non-XML characters private String checkedString(String value) { if (value == null) { return null; } String reason = Verifier.checkCharacterData(value); if (reason == null) { return value; } else { if (log.isDebugEnabled()) { log.debug("Filtering out non-XML characters in string, reason=" + reason); } StringBuffer result = new StringBuffer(value.length()); for (int i = 0; i < value.length(); ++i) { char c = value.charAt(i); if (Verifier.isXMLCharacter((int) c)) { result.append(c); } } return result.toString(); } } }