/* * 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; java.lang.ClassLoader loader = NewInstance.getClassLoader(); // 1. try the JVM-instance-wide system property try { className = java.lang.SystemJ.getProperty(property); } catch (java.lang.RuntimeException e) { /* normally fails for applets */ } // 2. if that fails, try META-INF/services/ if (className == null) { try { String service = "META-INF/services/" + property; java.io.InputStream input; java.io.BufferedReader reader; if (loader == null) { input = java.lang.ClassLoader.getSystemResourceAsStream(service); } else { input = loader.getResourceAsStream(service); } if (input != null) { reader = new java.io.BufferedReader( new java.io.InputStreamReader(input, "UTF8")); className = reader.readLine(); input.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... //Take a look in Java 7 shows: className = "com.sun.org.apache.xerces.internal.parsers.SAXParser"; // 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 (java.lang.Exception e) { throw new SAXException("Can't create default XMLReader; " + "is system property org.xml.sax.driver set?"); } }