XMLReaderpublic interface XMLReader Interface for reading an XML document using callbacks.
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.
Note: despite its name, this interface does
not extend the standard Java {@link java.io.Reader Reader}
interface, because reading XML is a fundamentally different activity
than reading character data.
XMLReader is the interface that an XML parser's SAX2 driver must
implement. This interface allows an application to set and
query features and properties in the parser, to register
event handlers for document processing, and to initiate
a document parse.
All SAX interfaces are assumed to be synchronous: the
{@link #parse parse} methods must not return until parsing
is complete, and readers must wait for an event-handler callback
to return before reporting the next event.
This interface replaces the (now deprecated) SAX 1.0 {@link
org.xml.sax.Parser Parser} interface. The XMLReader interface
contains two important enhancements over the old Parser
interface (as well as some minor ones):
- it adds a standard way to query and set features and
properties; and
- it adds Namespace support, which is required for many
higher-level XML standards.
There are adapters available to convert a SAX1 Parser to
a SAX2 XMLReader and vice-versa. |
| Methods Summary |
|---|
| public org.xml.sax.ContentHandler | getContentHandler()Return the current content handler.
| | public org.xml.sax.DTDHandler | getDTDHandler()Return the current DTD handler.
| | public org.xml.sax.EntityResolver | getEntityResolver()Return the current entity resolver.
| | public org.xml.sax.ErrorHandler | getErrorHandler()Return the current error handler.
| | public boolean | getFeature(java.lang.String name)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 {@link 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.
| | public java.lang.Object | getProperty(java.lang.String name)Look up the value of a property.
The property name is any fully-qualified URI. It is
possible for an XMLReader to recognize a property name but
temporarily be unable to return its value.
Some property values may be available only in specific
contexts, such as before, during, or after a parse.
XMLReaders are not required to recognize any specific
property names, though an initial core set is documented for
SAX2.
Implementors are free (and encouraged) to invent their own properties,
using names built on their own URIs.
| | public void | parse(org.xml.sax.InputSource input)Parse an XML document.
The application can use this method to instruct the XML
reader to begin parsing an XML document from any valid input
source (a character stream, a byte stream, or a URI).
Applications may not invoke this method while a parse is in
progress (they should create a new XMLReader instead for each
nested XML document). Once a parse is complete, an
application may reuse the same XMLReader object, possibly with a
different input source.
Configuration of the XMLReader object (such as handler bindings and
values established for feature flags and properties) is unchanged
by completion of a parse, unless the definition of that aspect of
the configuration explicitly specifies other behavior.
(For example, feature flags or properties exposing
characteristics of the document being parsed.)
During the parse, the XMLReader will provide information
about the XML document through the registered event
handlers.
This method is synchronous: it will not return until parsing
has ended. If a client application wants to terminate
parsing early, it should throw an exception.
| | public void | parse(java.lang.String systemId)Parse an XML document from a system identifier (URI).
This method is a shortcut for the common case of reading a
document from a system identifier. It is the exact
equivalent of the following:
parse(new InputSource(systemId));
If the system identifier is a URL, it must be fully resolved
by the application before it is passed to the parser.
| | public void | setContentHandler(org.xml.sax.ContentHandler handler)Allow an application to register a content event handler.
If the application does not register a content handler, all
content events reported by the SAX parser will be silently
ignored.
Applications may register a new or different handler in the
middle of a parse, and the SAX parser must begin using the new
handler immediately.
| | public void | setDTDHandler(org.xml.sax.DTDHandler handler)Allow an application to register a DTD event handler.
If the application does not register a DTD handler, all DTD
events reported by the SAX parser will be silently ignored.
Applications may register a new or different handler in the
middle of a parse, and the SAX parser must begin using the new
handler immediately.
| | public void | setEntityResolver(org.xml.sax.EntityResolver resolver)Allow an application to register an entity resolver.
If the application does not register an entity resolver,
the XMLReader will perform its own default resolution.
Applications may register a new or different resolver in the
middle of a parse, and the SAX parser must begin using the new
resolver immediately.
| | public void | setErrorHandler(org.xml.sax.ErrorHandler handler)Allow an application to register an error event handler.
If the application does not register an error handler, all
error events reported by the SAX parser will be silently
ignored; however, normal processing may not continue. It is
highly recommended that all SAX applications implement an
error handler to avoid unexpected bugs.
Applications may register a new or different handler in the
middle of a parse, and the SAX parser must begin using the new
handler immediately.
| | public void | setFeature(java.lang.String name, boolean value)Set the value of a feature flag.
The feature name is any fully-qualified URI. It is
possible for an XMLReader to expose a feature value but
to be unable to change the current value.
Some feature values may be immutable or mutable only
in specific contexts, such as before, during, or after
a parse.
All XMLReaders are required to support setting
http://xml.org/sax/features/namespaces to true and
http://xml.org/sax/features/namespace-prefixes to false.
| | public void | setProperty(java.lang.String name, java.lang.Object value)Set the value of a property.
The property name is any fully-qualified URI. It is
possible for an XMLReader to recognize a property name but
to be unable to change the current value.
Some property values may be immutable or mutable only
in specific contexts, such as before, during, or after
a parse.
XMLReaders are not required to recognize setting
any specific property names, though a core set is defined by
SAX2.
This method is also the standard mechanism for setting
extended handlers.
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