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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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// XMLReaderFactory.java - factory for creating a new reader.
// http://www.saxproject.org
// Written by David Megginson
// and by David Brownell
// NO WARRANTY! This class is in the Public Domain.
// $Id: XMLReaderFactory.java,v 1.2.2.1 2005/07/31 22:48:08 jeffsuttor Exp $
package org.xml.sax.helpers;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Iterator;
import java.util.Objects;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
/**
* Factory for creating an XML reader.
*
* <blockquote>
* <em>This module, both source code and documentation, is in the
* Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
* See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
* for further information.
* </blockquote>
*
* <p>This class contains static methods for creating an XML reader
* from an explicit class name, or based on runtime defaults:
*
* <pre>
* try {
* XMLReader myReader = XMLReaderFactory.createXMLReader();
* } catch (SAXException e) {
* System.err.println(e.getMessage());
* }
* </pre>
*
* <p><strong>Note to Distributions bundled with parsers:</strong>
* You should modify the implementation of the no-arguments
* <em>createXMLReader</em> to handle cases where the external
* configuration mechanisms aren't set up. That method should do its
* best to return a parser when one is in the class path, even when
* nothing bound its class name to {@code org.xml.sax.driver} so
* those configuration mechanisms would see it.
*
* @since 1.4, SAX 2.0
* @author David Megginson, David Brownell
* @version 2.0.1 (sax2r2)
*
* @deprecated It is recommended to use {@link javax.xml.parsers.SAXParserFactory}
* instead.
*/
@Deprecated(since="9")
final public class XMLReaderFactory
{
/**
* Private constructor.
*
* <p>This constructor prevents the class from being instantiated.
*/
private XMLReaderFactory ()
{
}
private static final String property = "org.xml.sax.driver";
private static final SecuritySupport ss = new SecuritySupport();
/**
* Obtains a new instance of a {@link org.xml.sax.XMLReader}.
* This method uses the following ordered lookup procedure to find and load
* the {@link org.xml.sax.XMLReader} implementation class:
* <p>
* <ol>
* <li>If the system property {@code org.xml.sax.driver}
* has a value, that is used as an XMLReader class name. </li>
* <li>
* Use the service-provider loading facility, defined by the
* {@link java.util.ServiceLoader} class, to attempt to locate and load an
* implementation of the service {@link org.xml.sax.XMLReader} by using the
* {@linkplain java.lang.Thread#getContextClassLoader() current thread's context class loader}.
* If the context class loader is null, the
* {@linkplain ClassLoader#getSystemClassLoader() system class loader} will
* be used.
* </li>
* <li>
* Deprecated. Look for a class name in the {@code META-INF/services/org.xml.sax.driver}
* file in a jar file available to the runtime.</li>
* <li>
* <p>
* Otherwise, the system-default implementation is returned.
* </li>
* </ol>
*
* @apiNote
* The process that looks for a class name in the
* {@code META-INF/services/org.xml.sax.driver} file in a jar file does not
* conform to the specification of the service-provider loading facility
* as defined in {@link java.util.ServiceLoader} and therefore does not
* support modularization. It is deprecated as of Java SE 9 and subject to
* removal in a future release.
*
* @return a new XMLReader.
* @exception org.xml.sax.SAXException If no default XMLReader class
* can be identified and instantiated.
* @see #createXMLReader(java.lang.String)
*/
public static XMLReader createXMLReader ()
throws SAXException
{
String className = null;
ClassLoader cl = ss.getClassLoader();
// 1. try the JVM-instance-wide system property
try {
className = ss.getSystemProperty(property);
}
catch (RuntimeException e) { /* continue searching */ }
// 2. try the ServiceLoader
if (className == null) {
final XMLReader provider = findServiceProvider(XMLReader.class, cl);
if (provider != null) {
return provider;
}
}
// 3. try META-INF/services/org.xml.sax.driver. This old process allows
// legacy providers to be found
if (className == null) {
className = jarLookup(cl);
}
// 4. Distro-specific fallback
if (className == null) {
return new com.sun.org.apache.xerces.internal.parsers.SAXParser();
}
return loadClass (cl, className);
}
/**
* Attempt to create an XML reader from a class name.
*
* <p>Given a class name, this method attempts to load
* and instantiate the class as an XML reader.
*
* <p>Note that this method will not be usable in environments where
* the caller (perhaps an applet) is not permitted to load classes
* dynamically.
*
* @return A new XML reader.
* @exception org.xml.sax.SAXException If the class cannot be
* loaded, instantiated, and cast to XMLReader.
* @see #createXMLReader()
*/
public static XMLReader createXMLReader (String className)
throws SAXException
{
return loadClass (ss.getClassLoader(), className);
}
private static XMLReader loadClass (ClassLoader loader, String className)
throws SAXException
{
try {
return NewInstance.newInstance (XMLReader.class, loader, className);
} catch (ClassNotFoundException e1) {
throw new SAXException("SAX2 driver class " + className +
" not found", e1);
} catch (IllegalAccessException e2) {
throw new SAXException("SAX2 driver class " + className +
" found but cannot be loaded", e2);
} catch (InstantiationException e3) {
throw new SAXException("SAX2 driver class " + className +
" loaded but cannot be instantiated (no empty public constructor?)",
e3);
} catch (ClassCastException e4) {
throw new SAXException("SAX2 driver class " + className +
" does not implement XMLReader", e4);
}
}
/**
* Locates a provider by directly reading the jar service file.
* @param loader the ClassLoader to be used to read the service file
* @return the name of the provider, or null if nothing is found
*/
private static String jarLookup(final ClassLoader loader) {
final ClassLoader cl = Objects.requireNonNull(loader);
String clsFromJar = null;
String service = "META-INF/services/" + property;
InputStream in;
BufferedReader reader;
try {
in = ss.getResourceAsStream(cl, service);
// If no provider found then try the current ClassLoader
if (in == null) {
in = ss.getResourceAsStream(null, service);
}
if (in != null) {
reader = new BufferedReader (new InputStreamReader (in, "UTF8"));
clsFromJar = reader.readLine ();
in.close ();
}
} catch (IOException e) {
}
return clsFromJar;
}
/*
* Try to find provider using the ServiceLoader API
*
* @param type Base class / Service interface of the factory to find.
*
* @return instance of provider class if found or null
*/
private static <T> T findServiceProvider(final Class<T> type, final ClassLoader loader)
throws SAXException {
ClassLoader cl = Objects.requireNonNull(loader);
try {
return AccessController.doPrivileged((PrivilegedAction<T>) () -> {
final ServiceLoader<T> serviceLoader;
serviceLoader = ServiceLoader.load(type, cl);
final Iterator<T> iterator = serviceLoader.iterator();
if (iterator.hasNext()) {
return iterator.next();
} else {
return null;
}
});
} catch(ServiceConfigurationError e) {
final RuntimeException x = new RuntimeException(
"Provider for " + type + " cannot be created", e);
throw new SAXException("Provider for " + type + " cannot be created", x);
}
}
}