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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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// SAX entity resolver.

// http://www.saxproject.org

// No warranty; no copyright -- use this as you will.

// $Id: EntityResolver.java,v 1.2 2004/11/03 22:44:52 jsuttor Exp $

package org.xml.sax;

import java.io.IOException;

/**

 * Basic interface for resolving entities.

 *

 * <blockquote>

 * <em>This module, both source code and documentation, is in the

 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>

 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>

 * for further information.

 * </blockquote>

 *

 * <p>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.</p>

 *

 * <p>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.</p>

 *

 * <p>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.</p>

 *

 * <p>The following resolver would provide the application

 * with a special character stream for the entity with the system

 * identifier "http://www.myhost.com/today":</p>

 *

 * <pre>

 * 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;

 *     }

 *   }

 * }

 * </pre>

 *

 * <p>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).</p>

 *

 * @since 1.4, SAX 1.0

 * @author David Megginson

 * @see org.xml.sax.XMLReader#setEntityResolver

 * @see org.xml.sax.InputSource

 */

public interface EntityResolver {

    /**

     * Allow the application to resolve external entities.

     *

     * <p>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).</p>

     *

     * <p>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.  </p>

     *

     * <p>If the system identifier is a URL, the SAX parser must

     * resolve it fully before reporting it to the application.</p>

     *

     * @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