| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| |
| /* $Id$ */ |
| |
| package org.apache.fop.render; |
| |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| import org.apache.xmlgraphics.util.Service; |
| |
| /** |
| * This class holds references to various XML handlers used by FOP. It also |
| * supports automatic discovery of additional XML handlers available through |
| * the class path. |
| */ |
| public class XMLHandlerRegistry { |
| |
| /** the logger */ |
| private static Log log = LogFactory.getLog(XMLHandlerRegistry.class); |
| |
| /** Map containing XML handlers for various document types */ |
| private Map<String, List<XMLHandler>> handlers |
| = new java.util.HashMap<String, List<XMLHandler>>(); |
| |
| /** |
| * Default constructor. |
| */ |
| public XMLHandlerRegistry() { |
| discoverXMLHandlers(); |
| } |
| |
| /** |
| * Add a default XML handler which is able to handle any namespace. |
| * @param handler XMLHandler to use |
| */ |
| private void setDefaultXMLHandler(XMLHandler handler) { |
| addXMLHandler(XMLHandler.HANDLE_ALL, handler); |
| } |
| |
| /** |
| * Add an XML handler. The handler itself is inspected to find out what it supports. |
| * @param classname the fully qualified class name |
| */ |
| public void addXMLHandler(String classname) { |
| try { |
| XMLHandler handlerInstance = (XMLHandler)Class.forName(classname).newInstance(); |
| addXMLHandler(handlerInstance); |
| } catch (ClassNotFoundException e) { |
| throw new IllegalArgumentException("Could not find " |
| + classname); |
| } catch (InstantiationException e) { |
| throw new IllegalArgumentException("Could not instantiate " |
| + classname); |
| } catch (IllegalAccessException e) { |
| throw new IllegalArgumentException("Could not access " |
| + classname); |
| } catch (ClassCastException e) { |
| throw new IllegalArgumentException(classname |
| + " is not an " |
| + XMLHandler.class.getName()); |
| } |
| } |
| |
| /** |
| * Add an XML handler. The handler itself is inspected to find out what it supports. |
| * @param handler the XMLHandler instance |
| */ |
| public void addXMLHandler(XMLHandler handler) { |
| String ns = handler.getNamespace(); |
| if (ns == null) { |
| setDefaultXMLHandler(handler); |
| } else { |
| addXMLHandler(ns, handler); |
| } |
| } |
| |
| /** |
| * Add an XML handler for the given MIME type and XML namespace. |
| * @param ns Namespace URI |
| * @param handler XMLHandler to use |
| */ |
| private void addXMLHandler(String ns, XMLHandler handler) { |
| List<XMLHandler> lst = handlers.get(ns); |
| if (lst == null) { |
| lst = new java.util.ArrayList<XMLHandler>(); |
| handlers.put(ns, lst); |
| } |
| lst.add(handler); |
| } |
| |
| /** |
| * Returns an XMLHandler which handles an XML dialect of the given namespace and for |
| * a specified output format defined by its MIME type. |
| * @param renderer the Renderer for which to retrieve a Renderer |
| * @param ns the XML namespace associated with the XML to be rendered |
| * @return the XMLHandler responsible for handling the XML or null if none is available |
| */ |
| public XMLHandler getXMLHandler(Renderer renderer, String ns) { |
| XMLHandler handler; |
| |
| List<XMLHandler> lst = handlers.get(ns); |
| handler = getXMLHandler(renderer, lst); |
| if (handler == null) { |
| lst = handlers.get(XMLHandler.HANDLE_ALL); |
| handler = getXMLHandler(renderer, lst); |
| } |
| return handler; |
| } |
| |
| private XMLHandler getXMLHandler(Renderer renderer, List<XMLHandler> lst) { |
| XMLHandler handler; |
| if (lst != null) { |
| for (int i = 0, c = lst.size(); i < c; i++) { |
| //TODO Maybe add priorities later |
| handler = lst.get(i); |
| if (handler.supportsRenderer(renderer)) { |
| return handler; |
| } |
| } |
| } |
| return null; //No handler found |
| } |
| |
| /** |
| * Discovers XMLHandler implementations through the classpath and dynamically |
| * registers them. |
| */ |
| private void discoverXMLHandlers() { |
| // add mappings from available services |
| Iterator<Object> providers = Service.providers(XMLHandler.class); |
| if (providers != null) { |
| while (providers.hasNext()) { |
| XMLHandler handler = (XMLHandler)providers.next(); |
| try { |
| if (log.isDebugEnabled()) { |
| log.debug("Dynamically adding XMLHandler: " + handler.getClass().getName()); |
| } |
| addXMLHandler(handler); |
| } catch (IllegalArgumentException e) { |
| log.error("Error while adding XMLHandler", e); |
| } |
| |
| } |
| } |
| } |
| } |