xwikiuriresolver.java

来自「xwiki 源码」· Java 代码 · 共 89 行

/**
 * ===================================================================
 *
 * Copyright (c) 2003,2004 Ludovic Dubost, All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 Lesser General Public License for more details, published at 
 * http://www.gnu.org/copyleft/lesser.html or in lesser.txt in the
 * root folder of this distribution.

 * Created by
 * User: Ludovic Dubost
 * Date: 27 ao鹴 2004
 * Time: 16:18:06
 */
package com.xpn.xwiki.pdf.impl;

import org.xml.sax.InputSource;
import org.xml.sax.EntityResolver;
import org.xml.sax.SAXException;

import java.net.URI;
import java.net.URISyntaxException;
import java.io.IOException;
import java.io.InputStream;
import java.io.File;

public class XWikiURIResolver implements EntityResolver {

    /**
     * Allow the application to resolve external entities.
     * <p/>
     * <p>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.</p>
     * <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).</p>
     * <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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *                                  wrapping another exception.
     * @throws 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 InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
        try {
            URI uri = new URI(systemId);

            if ("http".equals(uri.getScheme())) {
                String filename = (new File(uri.getPath())).getName();
                InputStream istream =  getClass().getClassLoader().getResourceAsStream(filename);
                return new InputSource(istream);
            } else if ("file".equals(uri.getScheme())) {
                String filename = (new File(uri.getPath())).getName();
                InputStream istream =  getClass().getClassLoader().getResourceAsStream(filename);
                return new InputSource(istream);                
            }
        } catch (URISyntaxException e) {
        }
        // Returning null causes the caller to try accessing the href
        return null;
    }
}