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
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 Parser interface. The XMLReader interface
contains two important enhancements over the old Parser
interface (as well as some minor ones):
There are adapters available to convert a SAX1 Parser to a SAX2 XMLReader and vice-versa.
API Note
Despite its name, this interface does
not extend the standard Java Reader
interface, because reading XML is a fundamentally different activity
than reading character data.
org.xml.sax.XMLFilter , org.xml.sax.helpers.ParserAdapter , org.xml.sax.helpers.XMLReaderAdapter
| Modifier and Type | Method and Description |
|---|---|
| public ContentHandler | Returns: The current content handler, or null if none has been registered.Return the current content handler. |
| public DTDHandler | Returns: The current DTD handler, or null if none has been registered.Return the current DTD handler. |
| public EntityResolver | Returns: The current entity resolver, or null if none has been registered.Return the current entity resolver. |
| public ErrorHandler | Returns: The current error handler, or null if none has been registered.Return the current error handler. |
| public boolean | Returns: The current value of the feature (true or false).The feature name, which is a fully-qualified URI. name)Look up the value of a feature flag. |
| public Object | Returns: The current value of the property.The property name, which is a fully-qualified URI. name)Look up the value of a property. |
| public void | parse(InputSource
The input source for the top-level of the
XML document. input)Parse an XML document. |
| public void | |
| public void | setContentHandler(ContentHandler
The content handler. handler)Allow an application to register a content event handler. |
| public void | setDTDHandler(DTDHandler
The DTD handler. handler)Allow an application to register a DTD event handler. |
| public void | setEntityResolver(EntityResolver
The entity resolver. resolver)Allow an application to register an entity resolver. |
| public void | setErrorHandler(ErrorHandler
The error handler. handler)Allow an application to register an error event handler. |
| public void | setFeature(String
The feature name, which is a fully-qualified URI. name, boolean The requested value of the feature (true or false). value)Set the value of a feature flag. |
| public void | setProperty(String
The property name, which is a fully-qualified URI. name, Object The requested value for the property. value)Set the value of a property. |
| getContentHandler | back to summary |
|---|---|
| public ContentHandler getContentHandler() Return the current content handler.
| |
| getDTDHandler | back to summary |
|---|---|
| public DTDHandler getDTDHandler() Return the current DTD handler.
| |
| getEntityResolver | back to summary |
|---|---|
| public EntityResolver getEntityResolver() Return the current entity resolver.
| |
| getErrorHandler | back to summary |
|---|---|
| public ErrorHandler getErrorHandler() Return the current error handler.
| |
| getFeature | back to summary |
|---|---|
| public boolean getFeature(String name) throws SAXNotRecognizedException, SAXNotSupportedException 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 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.
| |
| getProperty | back to summary |
|---|---|
| public Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException 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.
| |
| parse | back to summary |
|---|---|
| public void parse(InputSource input) throws IOException, SAXException 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.
| |
| parse | back to summary |
|---|---|
| public void parse(String systemId) throws IOException, SAXException 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.
| |
| setContentHandler | back to summary |
|---|---|
| public void setContentHandler(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.
| |
| setDTDHandler | back to summary |
|---|---|
| public void setDTDHandler(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.
| |
| setEntityResolver | back to summary |
|---|---|
| public void setEntityResolver(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.
| |
| setErrorHandler | back to summary |
|---|---|
| public void setErrorHandler(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.
| |
| setFeature | back to summary |
|---|---|
| public void setFeature(String name, boolean value) throws SAXNotRecognizedException, SAXNotSupportedException 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.
| |
| setProperty | back to summary |
|---|---|
| public void setProperty(String name, Object value) throws SAXNotRecognizedException, SAXNotSupportedException 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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