- // EntityResolver2.java - Extended SAX entity resolver.
- // http://www.saxproject.org
- // No warranty; no copyright -- use this as you will.
- // $Id: EntityResolver2.java,v 1.1.2.1 2004/05/01 08:34:43 jsuttor Exp $
-
- package org.xml.sax.ext;
-
- import java.io.IOException;
-
- import org.xml.sax.EntityResolver;
- import org.xml.sax.InputSource;
- import org.xml.sax.XMLReader;
- import org.xml.sax.SAXException;
-
-
- /**
- * Extended interface for mapping external entity references to input
- * sources, or providing a missing external subset. The
- * {@link XMLReader#setEntityResolver XMLReader.setEntityResolver()} method
- * is used to provide implementations of this interface to parsers.
- * When a parser uses the methods in this interface, the
- * {@link EntityResolver2#resolveEntity EntityResolver2.resolveEntity()}
- * method (in this interface) is used <em>instead of</em> the older (SAX 1.0)
- * {@link EntityResolver#resolveEntity EntityResolver.resolveEntity()} method.
- *
- * <blockquote>
- * <em>This module, both source code and documentation, is in the
- * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
- * </blockquote>
- *
- * <p>If a SAX application requires the customized handling which this
- * interface defines for external entities, it must ensure that it uses
- * an XMLReader with the
- * <em>http://xml.org/sax/features/use-entity-resolver2</em> feature flag
- * set to <em>true</em> (which is its default value when the feature is
- * recognized). If that flag is unrecognized, or its value is false,
- * or the resolver does not implement this interface, then only the
- * {@link EntityResolver} method will be used.
- * </p>
- *
- * <p>That supports three categories of application that modify entity
- * resolution. <em>Old Style</em> applications won't know about this interface;
- * they will provide an EntityResolver.
- * <em>Transitional Mode</em> provide an EntityResolver2 and automatically
- * get the benefit of its methods in any systems (parsers or other tools)
- * supporting it, due to polymorphism.
- * Both <em>Old Style</em> and <em>Transitional Mode</em> applications will
- * work with any SAX2 parser.
- * <em>New style</em> applications will fail to run except on SAX2 parsers
- * that support this particular feature.
- * They will insist that feature flag have a value of "true", and the
- * EntityResolver2 implementation they provide might throw an exception
- * if the original SAX 1.0 style entity resolution method is invoked.
- * </p>
- *
- * @see org.xml.sax.XMLReader#setEntityResolver
- *
- * @since SAX 2.0 (extensions 1.1 alpha)
- * @author David Brownell
- * @version TBD
- */
- public interface EntityResolver2 extends EntityResolver
- {
- /**
- * Allows applications to provide an external subset for documents
- * that don't explicitly define one. Documents with DOCTYPE declarations
- * that omit an external subset can thus augment the declarations
- * available for validation, entity processing, and attribute processing
- * (normalization, defaulting, and reporting types including ID).
- * This augmentation is reported
- * through the {@link LexicalHandler#startDTD startDTD()} method as if
- * the document text had originally included the external subset;
- * this callback is made before any internal subset data or errors
- * are reported.</p>
- *
- * <p>This method can also be used with documents that have no DOCTYPE
- * declaration. When the root element is encountered,
- * but no DOCTYPE declaration has been seen, this method is
- * invoked. If it returns a value for the external subset, that root
- * element is declared to be the root element, giving the effect of
- * splicing a DOCTYPE declaration at the end the prolog of a document
- * that could not otherwise be valid. The sequence of parser callbacks
- * in that case logically resembles this:</p>
- *
- * <pre>
- * ... comments and PIs from the prolog (as usual)
- * startDTD ("rootName", source.getPublicId (), source.getSystemId ());
- * startEntity ("[dtd]");
- * ... declarations, comments, and PIs from the external subset
- * endEntity ("[dtd]");
- * endDTD ();
- * ... then the rest of the document (as usual)
- * startElement (..., "rootName", ...);
- * </pre>
- *
- * <p>Note that the InputSource gets no further resolution.
- * Implementations of this method may wish to invoke
- * {@link #resolveEntity resolveEntity()} to gain benefits such as use
- * of local caches of DTD entities. Also, this method will never be
- * used by a (non-validating) processor that is not including external
- * parameter entities. </p>
- *
- * <p>Uses for this method include facilitating data validation when
- * interoperating with XML processors that would always require
- * undesirable network accesses for external entities, or which for
- * other reasons adopt a "no DTDs" policy.
- * Non-validation motives include forcing documents to include DTDs so
- * that attributes are handled consistently.
- * For example, an XPath processor needs to know which attibutes have
- * type "ID" before it can process a widely used type of reference.</p>
- *
- * <p><strong>Warning:</strong> Returning an external subset modifies
- * the input document. By providing definitions for general entities,
- * it can make a malformed document appear to be well formed.
- * </p>
- *
- * @param name Identifies the document root element. This name comes
- * from a DOCTYPE declaration (where available) or from the actual
- * root element.
- * @param baseURI The document's base URI, serving as an additional
- * hint for selecting the external subset. This is always an absolute
- * URI, unless it is null because the XMLReader was given an InputSource
- * without one.
- *
- * @return An InputSource object describing the new external subset
- * to be used by the parser, or null to indicate that no external
- * subset is provided.
- *
- * @exception SAXException Any SAX exception, possibly wrapping
- * another exception.
- * @exception IOException Probably indicating a failure to create
- * a new InputStream or Reader, or an illegal URL.
- */
- public InputSource getExternalSubset (String name, String baseURI)
- throws SAXException, IOException;
-
- /**
- * Allows applications to map references to external entities into input
- * sources, or tell the parser it should use conventional URI resolution.
- * This method is only called for external entities which have been
- * properly declared.
- * This method provides more flexibility than the {@link EntityResolver}
- * interface, supporting implementations of more complex catalogue
- * schemes such as the one defined by the <a href=
- "http://www.oasis-open.org/committees/entity/spec-2001-08-06.html"
- >OASIS XML Catalogs</a> specification.</p>
- *
- * <p>Parsers configured to use this resolver method will call it
- * to determine the input source to use for any external entity
- * being included because of a reference in the XML text.
- * That excludes the document entity, and any external entity returned
- * by {@link #getExternalSubset getExternalSubset()}.
- * When a (non-validating) processor is configured not to include
- * a class of entities (parameter or general) through use of feature
- * flags, this method is not invoked for such entities. </p>
- *
- * <p>Note that the entity naming scheme used here is the same one
- * used in the {@link LexicalHandler}, or in the {@link
- org.xml.sax.ContentHandler#skippedEntity
- ContentHandler.skippedEntity()}
- * method. </p>
- *
- * @param name Identifies the external entity being resolved.
- * Either "[dtd]" for the external subset, or a name starting
- * with "%" to indicate a parameter entity, or else the name of
- * a general entity. This is never null when invoked by a SAX2
- * parser.
- * @param publicId The public identifier of the external entity being
- * referenced (normalized as required by the XML specification), or
- * null if none was supplied.
- * @param baseURI The URI with respect to which relative systemIDs
- * are interpreted. This is always an absolute URI, unless it is
- * null (likely because the XMLReader was given an InputSource without
- * one). This URI is defined by the XML specification to be the one
- * associated with the "<" starting the relevant declaration.
- * @param systemId The system identifier of the external entity
- * being referenced; either a relative or absolute URI.
- * This is never null when invoked by a SAX2 parser; only declared
- * entities, and any external subset, are resolved by such parsers.
- *
- * @return An InputSource object describing the new input source to
- * be used by the parser. Returning null directs the parser to
- * resolve the system ID against the base URI and open a connection
- * to resulting URI.
- *
- * @exception SAXException Any SAX exception, possibly wrapping
- * another exception.
- * @exception IOException Probably indicating a failure to create
- * a new InputStream or Reader, or an illegal URL.
- */
- public InputSource resolveEntity (
- String name,
- String publicId,
- String baseURI,
- String systemId
- ) throws SAXException, IOException;
- }