org.xml.sax.helpers
public final class: XMLReaderFactory [javadoc |
source]
java.lang.Object
org.xml.sax.helpers.XMLReaderFactory
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.
- since:
SAX - 2.0
- author:
David - Megginson, David Brownell
| Method from org.xml.sax.helpers.XMLReaderFactory Detail: |
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...
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 (Exception e) {
throw new SAXException ("Can't create default XMLReader; "
+ "is system property org.xml.sax.driver set?");
}
}
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:
- If the system property
org.xml.sax.driver
has a value, that is used as an XMLReader class name.
- The JAR "Services API" is used to look for a class name
in the META-INF/services/org.xml.sax.driver file in
jarfiles available to the runtime.
- 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.
- Finally, if ParserFactory#makeParser() can
return a system default SAX1 parser, that parser is wrapped in
a ParserAdapter . (This is a migration aid for SAX1
environments, where the
org.xml.sax.parser system
property will often be usable.)
In environments such as small embedded systems, which can not
support that flexibility, other mechanisms to determine the default
may be used.
Note that many Java environments allow system properties to be
initialized on a command line. This means that in most cases
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.
|
public static XMLReader createXMLReader(String className) throws SAXException {
return loadClass (NewInstance.getClassLoader (), 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. |