utils.SafeSAX.java Source code

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Here is the source code for utils.SafeSAX.java

Source

/*
 * Copyright (C) 2009 Wilfried Elmenreich
 * Original project page: http://www.frevotool.tk
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License Version 3 as published
 * by the Free Software Foundation http://www.gnu.org/licenses/gpl-3.0.txt
 *
 * There is no warranty for this free software. The GPL requires that 
 * modified versions be marked as changed, so that their problems will
 * not be attributed erroneously to authors of pious versions.
 */

package utils;

import java.io.ByteArrayInputStream;
import java.io.File;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.SAXReader;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;

/**
 * This class is an extension of the original {@link org.dom4j.io.SAXReader}
 * with a safe <tt>dtd</tt> resolver. Silences missing dtd definition errors
 * during document loading.
 * 
 * The SafeSAX class serves as a "serial access" protocol for XML by
 * providing a static <b>read/1</b> method to load a given XML document.
 * If XML could not be loaded, it tries to load the XML document
 * with a generic resolver.
 * <p>
 * About SAX protocol:<br>
 * {@link http://www2.informatik.hu-berlin.de/~xing/Lib/Docs/jaxp/docs/tutorial/sax/index.html}
 * <p>
 * For further information about Java XML API, please visit:<br>
 * {@link http://www2.informatik.hu-berlin.de/~xing/Lib/Docs/jaxp/docs/tutorial/TOC.html#intro}
 * 
 * @author Wilfried Elmenreich
 */
public class SafeSAX {

    /**
     * Ignorant implementation of a dtd resolver, does not try to read a dtd but
     * delivers a generic xml dtd description instead
     */
    static EntityResolver resolver = new EntityResolver() {
        public InputSource resolveEntity(String publicId, String systemId) {
            return new InputSource(new ByteArrayInputStream("<?xml version='1.0' encoding='UTF-8'?>".getBytes()));
        }
    };

    /**
     * Creates a new SAXReader and tries to load the given file into an XML
     * document. In case the dtd could not be loaded, the process is restarted
     * using a generic resolver
     * 
     * @param loadFile
     *            the file to be loaded from
     * @param reportError if false, errors will be swallowed
     * @return the XML document
     */
    public static Document read(File loadFile, boolean reportError) {

        Document doc = null;
        boolean error = false;

        try {
            SAXReader xmlReader = new SAXReader(false);
            doc = xmlReader.read(loadFile);
        } catch (OutOfMemoryError mem) {
            System.err.println("Could not import! (Out of memory)");
        } catch (DocumentException e) {
            // System.err.println("Document type description could not be loaded (probably wrong path) - don't worry, using a generic dtd...");
            error = true;
        }

        if (error) {
            try {
                SAXReader xmlReader = new SAXReader(false);
                xmlReader.setEntityResolver(resolver);
                doc = xmlReader.read(loadFile);
            } catch (OutOfMemoryError mem) {
                System.err.println("Could not import! (Out of memory)");
            } catch (DocumentException e) {
                if (reportError) {
                    String msg = e.getMessage();
                    System.err.println("Error while import: DocumentException\n" + msg);
                }
                error = true;
            }
        }

        return doc;
    }
}