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; import com.sun.syndication.feed.WireFeed; import com.sun.syndication.io.impl.FeedGenerators; import org.jdom2.Document; import org.jdom2.JDOMException; import org.jdom2.output.DOMOutputter; import org.jdom2.output.Format; import org.jdom2.output.XMLOutputter; import java.io.IOException; import java.io.Writer; import java.io.File; import java.io.FileWriter; import java.util.List; import java.util.Map; import java.util.WeakHashMap; /** * Generates an XML document (String, File, OutputStream, Writer, W3C DOM document or JDOM document) * out of an WireFeed (RSS/Atom). * <p> * It generates all flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0 and 2.0) and * Atom 0.3 feeds. Generators are plugable (they must implement the ModuleParser interface). * <p> * @author Alejandro Abdelnur * */ public class WireFeedOutput { private static Map clMap = new WeakHashMap(); private static FeedGenerators getFeedGenerators() { synchronized (WireFeedOutput.class) { FeedGenerators generators = (FeedGenerators) clMap.get(Thread.currentThread().getContextClassLoader()); if (generators == null) { generators = new FeedGenerators(); clMap.put(Thread.currentThread().getContextClassLoader(), generators); } return generators; } } /** * Returns the list of supported output feed types. * <p> * @see WireFeed for details on the format of these strings. * <p> * @return a list of String elements with the supported output feed types. * */ public static List getSupportedFeedTypes() { return getFeedGenerators().getSupportedFeedTypes(); } /** * Creates a FeedOuput instance. * <p> * */ public WireFeedOutput() { } /** * Creates a String with the XML representation for the given WireFeed. * <p> * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is the responsibility * of the developer to ensure that if the String is written to a character stream the stream charset is the same as * the feed encoding property. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @return a String with the XML representation for the given WireFeed. * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws FeedException thrown if the XML representation for the feed could not be created. * */ public String outputString(WireFeed feed) throws IllegalArgumentException, FeedException { return outputString(feed, true); } /** * Creates a String with the XML representation for the given WireFeed. * <p> * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is the responsibility * of the developer to ensure that if the String is written to a character stream the stream charset is the same as * the feed encoding property. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @param prettyPrint pretty-print XML (true) oder collapsed * @return a String with the XML representation for the given WireFeed. * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws FeedException thrown if the XML representation for the feed could not be created. * */ public String outputString(WireFeed feed, boolean prettyPrint) throws IllegalArgumentException, FeedException { Document doc = outputJDom(feed); String encoding = feed.getEncoding(); Format format = prettyPrint ? Format.getPrettyFormat() : Format.getCompactFormat(); if (encoding != null) { format.setEncoding(encoding); } XMLOutputter outputter = new XMLOutputter(format); return outputter.outputString(doc); } /** * Creates a File containing with the XML representation for the given WireFeed. * <p> * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. The platform * default charset encoding is used to write the feed to the file. It is the responsibility * of the developer to ensure the feed encoding is set to the platform charset encoding. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @param file the file where to write the XML representation for the given WireFeed. * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws IOException thrown if there was some problem writing to the File. * @throws FeedException thrown if the XML representation for the feed could not be created. * */ public void output(WireFeed feed, File file) throws IllegalArgumentException, IOException, FeedException { output(feed, file, true); } /** * Creates a File containing with the XML representation for the given WireFeed. * <p> * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. The platform * default charset encoding is used to write the feed to the file. It is the responsibility * of the developer to ensure the feed encoding is set to the platform charset encoding. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @param file the file where to write the XML representation for the given WireFeed. * @param prettyPrint pretty-print XML (true) oder collapsed * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws IOException thrown if there was some problem writing to the File. * @throws FeedException thrown if the XML representation for the feed could not be created. * */ public void output(WireFeed feed, File file, boolean prettyPrint) throws IllegalArgumentException, IOException, FeedException { Writer writer = new FileWriter(file); output(feed, writer, prettyPrint); writer.close(); } /** * Writes to an Writer the XML representation for the given WireFeed. * <p> * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is the responsibility * of the developer to ensure the Writer instance is using the same charset encoding. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @param writer Writer to write the XML representation for the given WireFeed. * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws IOException thrown if there was some problem writing to the Writer. * @throws FeedException thrown if the XML representation for the feed could not be created. * */ public void output(WireFeed feed, Writer writer) throws IllegalArgumentException, IOException, FeedException { output(feed, writer, true); } /** * Writes to an Writer the XML representation for the given WireFeed. * <p> * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is the responsibility * of the developer to ensure the Writer instance is using the same charset encoding. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @param writer Writer to write the XML representation for the given WireFeed. * @param prettyPrint pretty-print XML (true) oder collapsed * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws IOException thrown if there was some problem writing to the Writer. * @throws FeedException thrown if the XML representation for the feed could not be created. * */ public void output(WireFeed feed, Writer writer, boolean prettyPrint) throws IllegalArgumentException, IOException, FeedException { Document doc = outputJDom(feed); String encoding = feed.getEncoding(); Format format = prettyPrint ? Format.getPrettyFormat() : Format.getCompactFormat(); if (encoding != null) { format.setEncoding(encoding); } XMLOutputter outputter = new XMLOutputter(format); outputter.output(doc, writer); } /** * Creates a W3C DOM document for the given WireFeed. * <p> * This method does not use the feed encoding property. * <p> * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'. * <p> * @param feed Abstract feed to create W3C DOM document from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @return the W3C DOM document for the given WireFeed. * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws FeedException thrown if the W3C DOM document for the feed could not be created. * */ public org.w3c.dom.Document outputW3CDom(WireFeed feed) throws IllegalArgumentException, FeedException { Document doc = outputJDom(feed); DOMOutputter outputter = new DOMOutputter(); try { return outputter.output(doc); } catch (JDOMException jdomEx) { throw new FeedException("Could not create DOM", jdomEx); } } /** * Creates a JDOM document for the given WireFeed. * <p> * This method does not use the feed encoding property. * <p> * NOTE: All other output methods delegate to this method. * <p> * @param feed Abstract feed to create JDOM document from. The type of the WireFeed must match * the type given to the FeedOuptut constructor. * @return the JDOM document for the given WireFeed. * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match. * @throws FeedException thrown if the JDOM document for the feed could not be created. * */ public Document outputJDom(WireFeed feed) throws IllegalArgumentException, FeedException { String type = feed.getFeedType(); WireFeedGenerator generator = getFeedGenerators().getGenerator(type); if (generator == null) { throw new IllegalArgumentException("Invalid feed type [" + type + "]"); } if (!generator.getType().equals(type)) { throw new IllegalArgumentException( "WireFeedOutput type[" + type + "] and WireFeed type [" + type + "] don't match"); } return generator.generate(feed); } }