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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/external/sax/org/xml/sax/helpers/XMLReaderFactory.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/external/sax/org/xml/sax/helpers/XMLReaderFactory.java | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/external/sax/org/xml/sax/helpers/XMLReaderFactory.java b/gcc-4.4.3/libjava/classpath/external/sax/org/xml/sax/helpers/XMLReaderFactory.java new file mode 100644 index 000000000..304f750b9 --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/external/sax/org/xml/sax/helpers/XMLReaderFactory.java @@ -0,0 +1,207 @@ +// 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 1.1 2004/12/23 22:38:42 mark 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 + + // CLASSPATH LOCAL: have to code in the backup. + // Among other things, see PR 31303, and this thread: + // http://gcc.gnu.org/ml/java-patches/2007-q1/msg00661.html + className = "gnu.xml.stream.SAXParser"; + + // 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); + } + } +} |