Java tutorial
/* * Copyright 2004 Sun Microsystems, Inc. * * 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 com.sun.syndication.io.impl; import com.sun.syndication.feed.module.DCModuleImpl; import com.sun.syndication.feed.module.DCSubjectImpl; import com.sun.syndication.feed.module.Module; import com.sun.syndication.feed.module.DCModule; import com.sun.syndication.feed.module.DCSubject; import com.sun.syndication.io.ModuleParser; import com.sun.syndication.io.WireFeedParser; import org.jdom2.Attribute; import org.jdom2.Element; import org.jdom2.Namespace; import java.util.ArrayList; import java.util.Iterator; import java.util.List; /** * Parser for the Dublin Core module. */ public class DCModuleParser implements ModuleParser { private static final String RDF_URI = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"; private static final String TAXO_URI = "http://purl.org/rss/1.0/modules/taxonomy/"; private static final Namespace DC_NS = Namespace.getNamespace(DCModule.URI); private static final Namespace RDF_NS = Namespace.getNamespace(RDF_URI); private static final Namespace TAXO_NS = Namespace.getNamespace(TAXO_URI); public final String getNamespaceUri() { return DCModule.URI; } private final Namespace getDCNamespace() { return DC_NS; } private final Namespace getRDFNamespace() { return RDF_NS; } private final Namespace getTaxonomyNamespace() { return TAXO_NS; } /** * Parse an element tree and return the module found in it. * <p> * @param dcRoot the root element containing the module elements. * @return the module parsed from the element tree, <i>null</i> if none. */ public Module parse(Element dcRoot) { boolean foundSomething = false; DCModule dcm = new DCModuleImpl(); List eList = dcRoot.getChildren("title", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setTitles(parseElementList(eList)); } eList = dcRoot.getChildren("creator", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setCreators(parseElementList(eList)); } eList = dcRoot.getChildren("subject", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setSubjects(parseSubjects(eList)); } eList = dcRoot.getChildren("description", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setDescriptions(parseElementList(eList)); } eList = dcRoot.getChildren("publisher", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setPublishers(parseElementList(eList)); } eList = dcRoot.getChildren("contributor", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setContributors(parseElementList(eList)); } eList = dcRoot.getChildren("date", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setDates(parseElementListDate(eList)); } eList = dcRoot.getChildren("type", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setTypes(parseElementList(eList)); } eList = dcRoot.getChildren("format", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setFormats(parseElementList(eList)); } eList = dcRoot.getChildren("identifier", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setIdentifiers(parseElementList(eList)); } eList = dcRoot.getChildren("source", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setSources(parseElementList(eList)); } eList = dcRoot.getChildren("language", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setLanguages(parseElementList(eList)); } eList = dcRoot.getChildren("relation", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setRelations(parseElementList(eList)); } eList = dcRoot.getChildren("coverage", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setCoverages(parseElementList(eList)); } eList = dcRoot.getChildren("rights", getDCNamespace()); if (eList.size() > 0) { foundSomething = true; dcm.setRightsList(parseElementList(eList)); } return (foundSomething) ? dcm : null; } /** * Utility method to parse a taxonomy from an element. * <p> * @param desc the taxonomy description element. * @return the string contained in the resource of the element. */ protected final String getTaxonomy(Element desc) { String d = null; Element taxo = desc.getChild("topic", getTaxonomyNamespace()); if (taxo != null) { Attribute a = taxo.getAttribute("resource", getRDFNamespace()); if (a != null) { d = a.getValue(); } } return d; } /** * Utility method to parse a list of subjects out of a list of elements. * <p> * @param eList the element list to parse. * @return a list of subjects parsed from the elements. */ protected final List parseSubjects(List eList) { List subjects = new ArrayList(); for (Iterator i = eList.iterator(); i.hasNext();) { Element eSubject = (Element) i.next(); Element eDesc = eSubject.getChild("Description", getRDFNamespace()); if (eDesc != null) { String taxonomy = getTaxonomy(eDesc); List eValues = eDesc.getChildren("value", getRDFNamespace()); for (Iterator v = eValues.iterator(); v.hasNext();) { Element eValue = (Element) v.next(); DCSubject subject = new DCSubjectImpl(); subject.setTaxonomyUri(taxonomy); subject.setValue(eValue.getText()); subjects.add(subject); } } else { DCSubject subject = new DCSubjectImpl(); subject.setValue(eSubject.getText()); subjects.add(subject); } } return subjects; } /** * Utility method to parse a list of strings out of a list of elements. * <p> * @param eList the list of elements to parse. * @return the list of strings */ protected final List parseElementList(List eList) { List values = new ArrayList(); for (Iterator i = eList.iterator(); i.hasNext();) { Element e = (Element) i.next(); values.add(e.getText()); } return values; } /** * Utility method to parse a list of dates out of a list of elements. * <p> * @param eList the list of elements to parse. * @return the list of dates. */ protected final List parseElementListDate(List eList) { List values = new ArrayList(); for (Iterator i = eList.iterator(); i.hasNext();) { Element e = (Element) i.next(); values.add(DateParser.parseDate(e.getText())); } return values; } }