// SAX entity resolver. // No warranty; no copyright -- use this as you will. // $Id: EntityResolver.java,v 1.1 2000/10/02 02:43:17 sboag Exp $ package org.xml.sax; import java.io.IOException; /** * Basic interface for resolving entities. * *
* This module, both source code and documentation, is in the * Public Domain, and comes with NO WARRANTY. ** *
If a SAX application needs to implement customized handling * for external entities, it must implement this interface and * register an instance with the SAX driver using the * {@link org.xml.sax.XMLReader#setEntityResolver setEntityResolver} * method.
* *The XML reader will then allow the application to intercept any * external entities (including the external DTD subset and external * parameter entities, if any) before including them.
* *Many SAX applications will not need to implement this interface, * but it will be especially useful for applications that build * XML documents from databases or other specialised input sources, * or for applications that use URI types other than URLs.
* *The following resolver would provide the application * with a special character stream for the entity with the system * identifier "http://www.myhost.com/today":
* ** import org.xml.sax.EntityResolver; * import org.xml.sax.InputSource; * * public class MyResolver implements EntityResolver { * public InputSource resolveEntity (String publicId, String systemId) * { * if (systemId.equals("http://www.myhost.com/today")) { * // return a special input source * MyReader reader = new MyReader(); * return new InputSource(reader); * } else { * // use the default behaviour * return null; * } * } * } ** *
The application can also use this interface to redirect system * identifiers to local URIs or to look up replacements in a catalog * (possibly by using the public identifier).
* * @since SAX 1.0 * @author David Megginson, * sax@megginson.com * @version 2.0 * @see org.xml.sax.Parser#setEntityResolver * @see org.xml.sax.InputSource */ public interface EntityResolver { /** * Allow the application to resolve external entities. * *The Parser will call this method before opening any external * entity except the top-level document entity (including the * external DTD subset, external entities referenced within the * DTD, and external entities referenced within the document * element): the application may request that the parser resolve * the entity itself, that it use an alternative URI, or that it * use an entirely different input source.
* *Application writers can use this method to redirect external * system identifiers to secure and/or local URIs, to look up * public identifiers in a catalogue, or to read an entity from a * database or other input source (including, for example, a dialog * box).
* *If the system identifier is a URL, the SAX parser must * resolve it fully before reporting it to the application.
* * @param publicId The public identifier of the external entity * being referenced, or null if none was supplied. * @param systemId The system identifier of the external entity * being referenced. * @return An InputSource object describing the new input source, * or null to request that the parser open a regular * URI connection to the system identifier. * @exception org.xml.sax.SAXException Any SAX exception, possibly * wrapping another exception. * @exception java.io.IOException A Java-specific IO exception, * possibly the result of creating a new InputStream * or Reader for the InputSource. * @see org.xml.sax.InputSource */ public abstract InputSource resolveEntity (String publicId, String systemId) throws SAXException, IOException; } // end of EntityResolver.java