net.yacy.document.parser.xml.OOXMLSharedStringsHandler.java Source code

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Here is the source code for net.yacy.document.parser.xml.OOXMLSharedStringsHandler.java

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// OOXMLSharedStringsHandler.java
// ---------------------------
// Copyright 2017 by luccioman; https://github.com/luccioman
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// LICENSE
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

package net.yacy.document.parser.xml;

import java.io.IOException;
import java.util.List;

import org.apache.commons.io.input.ClosedInputStream;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * SAX handler for Office Open XML SpreadSheet xl/sharedStrings.xml files.
 * 
 * @author luccioman
 * @see <a href=
 *      "http://www.ecma-international.org/publications/standards/Ecma-376.htm">Ecma
 *      Standard for Office Open XML File Formats</a>
 *
 */
public class OOXMLSharedStringsHandler extends DefaultHandler {

    /** The entry name of a shared strings table in an OOXML container */
    public static final String ENTRY_NAME = "xl/sharedStrings.xml";

    /** Name of a shared string tag */
    private static final String SHARED_STRING_TAG = "t";

    /** Shared strings list */
    private final List<String> sharedStrings;

    /** Currently parsed string builder. */
    private StringBuilder currentString;

    /**
     * @param sharedStrings
     *            the mutable list of shared strings to fill
     * @throws IllegalArgumentException
     *             when a parameter is null
     */
    public OOXMLSharedStringsHandler(final List<String> sharedStrings) throws IllegalArgumentException {
        if (sharedStrings == null) {
            throw new IllegalArgumentException("sharedStrings list must not be null");
        }
        this.sharedStrings = sharedStrings;
    }

    /**
     * @return an empty source to prevent the SAX parser opening an unwanted
     *         connection to resolve an external entity
     */
    @Override
    public InputSource resolveEntity(String publicId, String systemId) throws IOException, SAXException {
        return new InputSource(new ClosedInputStream());
    }

    @Override
    public void startDocument() throws SAXException {
        this.currentString = new StringBuilder();
    }

    @Override
    public void startElement(final String uri, final String localName, final String qName,
            final Attributes attributes) throws SAXException {
        if (SHARED_STRING_TAG.equals(qName)) {
            this.currentString.setLength(0);
        }
    }

    /**
     * Append characters to the current string builder. May be called multiple times
     * before obtaining the whole current element string.
     */
    @Override
    public void characters(final char ch[], final int start, final int length) throws SAXException {
        this.currentString.append(ch, start, length);
    }

    /**
     * Add the current string content to the list when ending a shared string
     * element
     */
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if (SHARED_STRING_TAG.equals(qName)) {
            final String sharedString = this.currentString.toString();
            this.sharedStrings.add(sharedString);
            this.currentString.setLength(0);
        }
    }

    @Override
    public void endDocument() throws SAXException {
        /* Release the StringBuilder now useless */
        this.currentString = null;
    }

}