- /*
- * Copyright 1999-2004 The Apache Software Foundation.
- *
- * 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.
- */
- /*
- * $Id: XMLReaderManager.java,v 1.2 2004/02/17 04:21:14 minchau Exp $
- */
- package com.sun.org.apache.xml.internal.utils;
-
- import java.util.Hashtable;
-
- import javax.xml.parsers.FactoryConfigurationError;
- import javax.xml.parsers.ParserConfigurationException;
- import javax.xml.parsers.SAXParserFactory;
-
- import org.xml.sax.XMLReader;
- import org.xml.sax.helpers.XMLReaderFactory;
- import org.xml.sax.SAXException;
-
- /**
- * Creates XMLReader objects and caches them for re-use.
- * This class follows the singleton pattern.
- */
- public class XMLReaderManager {
-
- private static final String NAMESPACES_FEATURE =
- "http://xml.org/sax/features/namespaces";
- private static final String NAMESPACE_PREFIXES_FEATURE =
- "http://xml.org/sax/features/namespace-prefixes";
- private static final XMLReaderManager m_singletonManager =
- new XMLReaderManager();
-
- /**
- * Parser factory to be used to construct XMLReader objects
- */
- private static SAXParserFactory m_parserFactory;
-
- /**
- * Cache of XMLReader objects
- */
- private ThreadLocal m_readers;
-
- /**
- * Keeps track of whether an XMLReader object is in use.
- */
- private Hashtable m_inUse;
-
- /**
- * Hidden constructor
- */
- private XMLReaderManager() {
- }
-
- /**
- * Retrieves the singleton reader manager
- */
- public static XMLReaderManager getInstance() {
- return m_singletonManager;
- }
-
- /**
- * Retrieves a cached XMLReader for this thread, or creates a new
- * XMLReader, if the existing reader is in use. When the caller no
- * longer needs the reader, it must release it with a call to
- * {@link releaseXMLReader}.
- */
- public synchronized XMLReader getXMLReader() throws SAXException {
- XMLReader reader;
- boolean readerInUse;
-
- if (m_readers == null) {
- // When the m_readers.get() method is called for the first time
- // on a thread, a new XMLReader will automatically be created.
- m_readers = new ThreadLocal();
- }
-
- if (m_inUse == null) {
- m_inUse = new Hashtable();
- }
-
- // If the cached reader for this thread is in use, construct a new
- // one; otherwise, return the cached reader.
- reader = (XMLReader) m_readers.get();
- boolean threadHasReader = (reader != null);
- if (!threadHasReader || m_inUse.get(reader) == Boolean.TRUE) {
- try {
- try {
- // According to JAXP 1.2 specification, if a SAXSource
- // is created using a SAX InputSource the Transformer or
- // TransformerFactory creates a reader via the
- // XMLReaderFactory if setXMLReader is not used
- reader = XMLReaderFactory.createXMLReader();
- } catch (Exception e) {
- try {
- // If unable to create an instance, let's try to use
- // the XMLReader from JAXP
- if (m_parserFactory == null) {
- m_parserFactory = SAXParserFactory.newInstance();
- m_parserFactory.setNamespaceAware(true);
- }
-
- reader = m_parserFactory.newSAXParser().getXMLReader();
- } catch (ParserConfigurationException pce) {
- throw pce; // pass along pce
- }
- }
- try {
- reader.setFeature(NAMESPACES_FEATURE, true);
- reader.setFeature(NAMESPACE_PREFIXES_FEATURE, false);
- } catch (SAXException se) {
- // Try to carry on if we've got a parser that
- // doesn't know about namespace prefixes.
- }
- } catch (ParserConfigurationException ex) {
- throw new SAXException(ex);
- } catch (FactoryConfigurationError ex1) {
- throw new SAXException(ex1.toString());
- } catch (NoSuchMethodError ex2) {
- } catch (AbstractMethodError ame) {
- }
-
- // Cache the XMLReader if this is the first time we've created
- // a reader for this thread.
- if (!threadHasReader) {
- m_readers.set(reader);
- m_inUse.put(reader, Boolean.TRUE);
- }
- } else {
- m_inUse.put(reader, Boolean.TRUE);
- }
-
- return reader;
- }
-
- /**
- * Mark the cached XMLReader as available. If the reader was not
- * actually in the cache, do nothing.
- *
- * @param reader The XMLReader that's being released.
- */
- public synchronized void releaseXMLReader(XMLReader reader) {
- // If the reader that's being released is the cached reader
- // for this thread, mark it as no longer being in use.
- if (m_readers.get() == reader) {
- m_inUse.put(reader, Boolean.FALSE);
- }
- }
- }