+ * 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 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; + +}