+ * 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. + *+ * + *
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 + * @version 2.0.1 (sax2r2) + * @see org.xml.sax.XMLReader#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. Such entities include + * the external DTD subset and external parameter entities referenced + * within the DTD (in either case, only if the parser reads external + * parameter entities), and external general entities referenced + * within the document element (if the parser reads external general + * entities). The application may request that the parser locate + * the entity itself, that it use an alternative URI, or that it + * use data provided by the application (as a character or byte + * input stream).
+ * + *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). Neither XML nor SAX specifies a preferred policy for using + * public or system IDs to resolve resources. However, SAX specifies + * how to interpret any InputSource returned by this method, and that + * if none is returned, then the system ID will be dereferenced as + * a URL.
+ * + *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