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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 jdk.xml.internal.SecuritySupport;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
Factory for creating an XML reader.
This module, both source code and documentation, is in the
Public Domain, and comes with NO WARRANTY.
See http://www.saxproject.org
for further information.
This class contains static methods for creating an XML reader
from an explicit class name, or based on runtime defaults:
try {
XMLReader myReader = XMLReaderFactory.createXMLReader();
} catch (SAXException e) {
System.err.println(e.getMessage());
}
Note to Distributions bundled with parsers:
You should modify the implementation of the no-arguments
createXMLReader 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 org.xml.sax.driver so those configuration mechanisms would see it.
Author: David Megginson, David Brownell Since: 1.4, SAX 2.0 Version: 2.0.1 (sax2r2) Deprecated: It is recommended to use SAXParserFactory instead.
/**
* 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.
This constructor prevents the class from being instantiated.
/**
* Private constructor.
*
* <p>This constructor prevents the class from being instantiated.
*/
private XMLReaderFactory ()
{
}
private static final String property = "org.xml.sax.driver";
Obtains a new instance of a XMLReader. This method uses the following ordered lookup procedure to find and load the XMLReader implementation class:
- If the system property
org.xml.sax.driver has a value, that is used as an XMLReader class name.
- Use the service-provider loading facility, defined by the
ServiceLoader class, to attempt to locate and load an implementation of the service XMLReader by using the current thread's context class loader. If the context class loader is null, the system class loader will be used.
- Deprecated. Look for a class name in the
META-INF/services/org.xml.sax.driver file in a jar file available to the runtime.
-
Otherwise, the system-default implementation is returned.
Throws: - SAXException – If no default XMLReader class
can be identified and instantiated.
See Also: API Note: The process that looks for a class name in the 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 ServiceLoader and therefore does not support modularization. It is deprecated as of Java SE 9 and subject to removal in a future release. Returns: a new XMLReader.
/**
* 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:
* <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 = SecuritySupport.getClassLoader();
// 1. try the JVM-instance-wide system property
try {
className = SecuritySupport.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.
Given a class name, this method attempts to load
and instantiate the class as an XML reader.
Note that this method will not be usable in environments where
the caller (perhaps an applet) is not permitted to load classes
dynamically.
Throws: - SAXException – If the class cannot be
loaded, instantiated, and cast to XMLReader.
See Also: Returns: A new XML reader.
/**
* 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 (SecuritySupport.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.
Params: - loader – the ClassLoader to be used to read the service file
Returns: the name of the provider, or null if nothing is found
/**
* 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 = SecuritySupport.getResourceAsStream(cl, service);
// If no provider found then try the current ClassLoader
if (in == null) {
in = SecuritySupport.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);
}
}
}