* 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):
* *There are adapters available to convert a SAX1 Parser to * a SAX2 XMLReader and vice-versa.
* * @since 1.4, SAX 2.0 * @author David Megginson * @see org.xml.sax.XMLFilter * @see org.xml.sax.helpers.ParserAdapter * @see org.xml.sax.helpers.XMLReaderAdapter */ public interface XMLReader { //////////////////////////////////////////////////////////////////// // Configuration. //////////////////////////////////////////////////////////////////// /** * 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.
* * @param name The feature name, which is a fully-qualified URI. * @return The current value of the feature (true or false). * @exception org.xml.sax.SAXNotRecognizedException If the feature * value can't be assigned or retrieved. * @exception org.xml.sax.SAXNotSupportedException When the * XMLReader recognizes the feature name but * cannot determine its value at this time. * @see #setFeature */ public boolean getFeature (String name) 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.
* * @param name The feature name, which is a fully-qualified URI. * @param value The requested value of the feature (true or false). * @exception org.xml.sax.SAXNotRecognizedException If the feature * value can't be assigned or retrieved. * @exception org.xml.sax.SAXNotSupportedException When the * XMLReader recognizes the feature name but * cannot set the requested value. * @see #getFeature */ public void setFeature (String name, boolean value) 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.
* * @param name The property name, which is a fully-qualified URI. * @return The current value of the property. * @exception org.xml.sax.SAXNotRecognizedException If the property * value can't be assigned or retrieved. * @exception org.xml.sax.SAXNotSupportedException When the * XMLReader recognizes the property name but * cannot determine its value at this time. * @see #setProperty */ public Object getProperty (String name) 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.
* * @param name The property name, which is a fully-qualified URI. * @param value The requested value for the property. * @exception org.xml.sax.SAXNotRecognizedException If the property * value can't be assigned or retrieved. * @exception org.xml.sax.SAXNotSupportedException When the * XMLReader recognizes the property name but * cannot set the requested value. */ public void setProperty (String name, Object value) throws SAXNotRecognizedException, SAXNotSupportedException; //////////////////////////////////////////////////////////////////// // Event handlers. //////////////////////////////////////////////////////////////////// /** * 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.
* * @param resolver The entity resolver. * @see #getEntityResolver */ public void setEntityResolver (EntityResolver resolver); /** * Return the current entity resolver. * * @return The current entity resolver, or null if none * has been registered. * @see #setEntityResolver */ public EntityResolver getEntityResolver (); /** * 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.
* * @param handler The DTD handler. * @see #getDTDHandler */ public void setDTDHandler (DTDHandler handler); /** * Return the current DTD handler. * * @return The current DTD handler, or null if none * has been registered. * @see #setDTDHandler */ public DTDHandler getDTDHandler (); /** * 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.
* * @param handler The content handler. * @see #getContentHandler */ public void setContentHandler (ContentHandler handler); /** * Return the current content handler. * * @return The current content handler, or null if none * has been registered. * @see #setContentHandler */ public ContentHandler getContentHandler (); /** * 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.
* * @param handler The error handler. * @see #getErrorHandler */ public void setErrorHandler (ErrorHandler handler); /** * Return the current error handler. * * @return The current error handler, or null if none * has been registered. * @see #setErrorHandler */ public ErrorHandler getErrorHandler (); //////////////////////////////////////////////////////////////////// // Parsing. //////////////////////////////////////////////////////////////////// /** * 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.
* * @param input The input source for the top-level of the * XML document. * @exception org.xml.sax.SAXException Any SAX exception, possibly * wrapping another exception. * @exception java.io.IOException An IO exception from the parser, * possibly from a byte stream or character stream * supplied by the application. * @see org.xml.sax.InputSource * @see #parse(java.lang.String) * @see #setEntityResolver * @see #setDTDHandler * @see #setContentHandler * @see #setErrorHandler */ public void parse (InputSource input) 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.
* * @param systemId The system identifier (URI). * @exception org.xml.sax.SAXException Any SAX exception, possibly * wrapping another exception. * @exception java.io.IOException An IO exception from the parser, * possibly from a byte stream or character stream * supplied by the application. * @see #parse(org.xml.sax.InputSource) */ public void parse (String systemId) throws IOException, SAXException; }