Java tutorial
/* * 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.rometools.feed.module.opensearch.impl; import java.net.MalformedURLException; import java.net.URL; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import org.jdom2.Attribute; import org.jdom2.Element; import org.jdom2.Namespace; import org.jdom2.Parent; import com.sun.syndication.feed.atom.Link; import com.sun.syndication.feed.module.Module; import org.rometools.feed.module.opensearch.OpenSearchModule; import org.rometools.feed.module.opensearch.entity.OSQuery; import com.sun.syndication.io.ModuleParser; /** * @author Michael W. Nassif (enrouteinc@gmail.com) * OpenSearch implementation of the ModuleParser class */ public class OpenSearchModuleParser implements ModuleParser { private static final Namespace OS_NS = Namespace.getNamespace("opensearch", OpenSearchModule.URI); public String getNamespaceUri() { return OpenSearchModule.URI; } public Module parse(Element dcRoot) { URL baseURI = findBaseURI(dcRoot); boolean foundSomething = false; OpenSearchModule osm = new OpenSearchModuleImpl(); Element e = dcRoot.getChild("totalResults", OS_NS); if (e != null) { foundSomething = true; try { osm.setTotalResults(Integer.parseInt(e.getText())); } catch (NumberFormatException ex) { // Ignore setting the field and post a warning System.err .println("Warning: The element totalResults must be an integer value: " + ex.getMessage()); } } e = dcRoot.getChild("itemsPerPage", OS_NS); try { osm.setItemsPerPage(Integer.parseInt(e.getText())); } catch (NumberFormatException ex) { // Ignore setting the field and post a warning System.err.println("Warning: The element itemsPerPage must be an integer value: " + ex.getMessage()); } e = dcRoot.getChild("startIndex", OS_NS); try { osm.setStartIndex(Integer.parseInt(e.getText())); } catch (NumberFormatException ex) { // Ignore setting the field and post a warning System.err.println("Warning: The element startIndex must be an integer value: " + ex.getMessage()); } List queries = dcRoot.getChildren("Query", OS_NS); if (queries != null && queries.size() > 0) { // Create the OSQuery list List osqList = new LinkedList(); for (Iterator iter = queries.iterator(); iter.hasNext();) { e = (Element) iter.next(); osqList.add(parseQuery(e)); } osm.setQueries(osqList); } e = dcRoot.getChild("link", OS_NS); if (e != null) { osm.setLink(parseLink(e, baseURI)); } return (foundSomething) ? osm : null; } private static OSQuery parseQuery(Element e) { OSQuery query = new OSQuery(); String att = e.getAttributeValue("role"); query.setRole(att); att = e.getAttributeValue("osd"); query.setOsd(att); att = e.getAttributeValue("searchTerms"); query.setSearchTerms(att); att = e.getAttributeValue("title"); query.setTitle(att); try { // someones mistake should not cause the parser to fail, since these are only optional attributes att = e.getAttributeValue("totalResults"); if (att != null) { query.setTotalResults(Integer.parseInt(att)); } att = e.getAttributeValue("startPage"); if (att != null) { query.setStartPage(Integer.parseInt(att)); } } catch (NumberFormatException ex) { System.err.println("Warning: Exception caught while trying to parse a non-numeric Query attribute " + ex.getMessage()); } return query; } private static Link parseLink(Element e, URL baseURI) { Link link = new Link(); String att = e.getAttributeValue("rel");//getAtomNamespace()); DONT KNOW WHY DOESN'T WORK if (att != null) { link.setRel(att); } att = e.getAttributeValue("type");//getAtomNamespace()); DONT KNOW WHY DOESN'T WORK if (att != null) { link.setType(att); } att = e.getAttributeValue("href");//getAtomNamespace()); DONT KNOW WHY DOESN'T WORK if (att != null) { if (isRelativeURI(att)) { // link.setHref(resolveURI(baseURI, e, "")); } else { link.setHref(att); } } att = e.getAttributeValue("hreflang");//getAtomNamespace()); DONT KNOW WHY DOESN'T WORK if (att != null) { link.setHreflang(att); } att = e.getAttributeValue("length");//getAtomNamespace()); DONT KNOW WHY DOESN'T WORK return link; } private static boolean isRelativeURI(String uri) { if (uri.startsWith("http://") || uri.startsWith("https://") || uri.startsWith("/")) { return false; } return true; } /** Use xml:base attributes at feed and entry level to resolve relative links */ private static String resolveURI(URL baseURI, Parent parent, String url) { url = (url.equals(".") || url.equals("./")) ? "" : url; if (isRelativeURI(url) && parent != null && parent instanceof Element) { Attribute baseAtt = ((Element) parent).getAttribute("base", Namespace.XML_NAMESPACE); String xmlBase = (baseAtt == null) ? "" : baseAtt.getValue(); if (!isRelativeURI(xmlBase) && !xmlBase.endsWith("/")) { xmlBase = xmlBase.substring(0, xmlBase.lastIndexOf("/") + 1); } return resolveURI(baseURI, parent.getParent(), xmlBase + url); } else if (isRelativeURI(url) && parent == null) { return baseURI + url; } else if (baseURI != null && url.startsWith("/")) { String hostURI = baseURI.getProtocol() + "://" + baseURI.getHost(); if (baseURI.getPort() != baseURI.getDefaultPort()) { hostURI = hostURI + ":" + baseURI.getPort(); } return hostURI + url; } return url; } /** Use feed links and/or xml:base attribute to determine baseURI of feed */ private static URL findBaseURI(Element root) { URL baseURI = null; List linksList = root.getChildren("link", OS_NS); if (linksList != null) { for (Iterator links = linksList.iterator(); links.hasNext();) { Element link = (Element) links.next(); if (!root.equals(link.getParent())) break; String href = link.getAttribute("href").getValue(); if (link.getAttribute("rel", OS_NS) == null || link.getAttribute("rel", OS_NS).getValue().equals("alternate")) { href = resolveURI(null, link, href); try { baseURI = new URL(href); break; } catch (MalformedURLException e) { System.err.println("Base URI is malformed: " + href); } } } } return baseURI; } }