--- /dev/null
+// 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 1.10 2002/04/22 01:00:13 dbrownell Exp $
+
+package org.xml.sax.helpers;
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import org.xml.sax.XMLReader;
+import org.xml.sax.SAXException;
+
+
+/**
+ * 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:</p>
+ *
+ * <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</code> so
+ * those configuration mechanisms would see it.</p>
+ *
+ * @since SAX 2.0
+ * @author David Megginson, David Brownell
+ * @version 2.0.1 (sax2r2)
+ */
+final public class XMLReaderFactory
+{
+ /**
+ * Private constructor.
+ *
+ * <p>This constructor prevents the class from being instantiated.</p>
+ */
+ private XMLReaderFactory ()
+ {
+ }
+
+ private static final String property = "org.xml.sax.driver";
+
+ /**
+ * Attempt to create an XMLReader from system defaults.
+ * In environments which can support it, the name of the XMLReader
+ * class is determined by trying each these options in order, and
+ * using the first one which succeeds:</p> <ul>
+ *
+ * <li>If the system property <code>org.xml.sax.driver</code>
+ * has a value, that is used as an XMLReader class name. </li>
+ *
+ * <li>The JAR "Services API" is used to look for a class name
+ * in the <em>META-INF/services/org.xml.sax.driver</em> file in
+ * jarfiles available to the runtime.</li>
+ *
+ * <li> SAX parser distributions are strongly encouraged to provide
+ * a default XMLReader class name that will take effect only when
+ * previous options (on this list) are not successful.</li>
+ *
+ * <li>Finally, if {@link ParserFactory#makeParser()} can
+ * return a system default SAX1 parser, that parser is wrapped in
+ * a {@link ParserAdapter}. (This is a migration aid for SAX1
+ * environments, where the <code>org.xml.sax.parser</code> system
+ * property will often be usable.) </li>
+ *
+ * </ul>
+ *
+ * <p> In environments such as small embedded systems, which can not
+ * support that flexibility, other mechanisms to determine the default
+ * may be used. </p>
+ *
+ * <p>Note that many Java environments allow system properties to be
+ * initialized on a command line. This means that <em>in most cases</em>
+ * setting a good value for that property ensures that calls to this
+ * method will succeed, except when security policies intervene.
+ * This will also maximize application portability to older SAX
+ * environments, with less robust implementations of this method.
+ * </p>
+ *
+ * @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 loader = NewInstance.getClassLoader ();
+
+ // 1. try the JVM-instance-wide system property
+ try { className = System.getProperty (property); }
+ catch (RuntimeException e) { /* normally fails for applets */ }
+
+ // 2. if that fails, try META-INF/services/
+ if (className == null) {
+ try {
+ String service = "META-INF/services/" + property;
+ InputStream in;
+ BufferedReader reader;
+
+ if (loader == null)
+ in = ClassLoader.getSystemResourceAsStream (service);
+ else
+ in = loader.getResourceAsStream (service);
+
+ if (in != null) {
+ reader = new BufferedReader (
+ new InputStreamReader (in, "UTF8"));
+ className = reader.readLine ();
+ in.close ();
+ }
+ } catch (Exception e) {
+ }
+ }
+
+ // 3. Distro-specific fallback
+ if (className == null) {
+// BEGIN DISTRIBUTION-SPECIFIC
+
+ // EXAMPLE:
+ // className = "com.example.sax.XmlReader";
+ // or a $JAVA_HOME/jre/lib/*properties setting...
+
+// END DISTRIBUTION-SPECIFIC
+ }
+
+ // do we know the XMLReader implementation class yet?
+ if (className != null)
+ return loadClass (loader, className);
+
+ // 4. panic -- adapt any SAX1 parser
+ try {
+ return new ParserAdapter (ParserFactory.makeParser ());
+ } catch (Exception e) {
+ throw new SAXException ("Can't create default XMLReader; "
+ + "is system property org.xml.sax.driver set?");
+ }
+ }
+
+
+ /**
+ * 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>
+ *
+ * <p>Note that this method will not be usable in environments where
+ * the caller (perhaps an applet) is not permitted to load classes
+ * dynamically.</p>
+ *
+ * @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 (NewInstance.getClassLoader (), className);
+ }
+
+ private static XMLReader loadClass (ClassLoader loader, String className)
+ throws SAXException
+ {
+ try {
+ return (XMLReader) NewInstance.newInstance (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);
+ }
+ }
+}
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