Look up the value of a feature flag.
The feature name is any fully-qualified URI. It is possible for an XMLReader to recognize a feature name but temporarily be unable to return its value. Some feature values may be available only in specific contexts, such as before, during, or after a parse. Also, some feature values may not be programmatically accessible. (In the case of an adapter for SAX1 Parser, there is no implementation-independent way to expose whether the underlying parser is performing validation, expanding external entities, and so forth.)
All XMLReaders are required to recognize the http://xml.org/sax/features/namespaces and the http://xml.org/sax/features/namespace-prefixes feature names.
Typical usage is something like this:
XMLReader r = new MySAXDriver();
// try to activate validation
try {
r.setFeature("http://xml.org/sax/features/validation", true);
} catch (SAXException e) {
System.err.println("Cannot activate validation.");
}
// register event handlers
r.setContentHandler(new MyContentHandler());
r.setErrorHandler(new MyErrorHandler());
// parse the first document
try {
r.parse("http://www.foo.com/mydoc.xml");
} catch (IOException e) {
System.err.println("I/O exception reading XML document");
} catch (SAXException e) {
System.err.println("XML exception reading document.");
}
Implementors are free (and encouraged) to invent their own features, using names built on their own URIs.