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// OOXMLSpreeadsheetHandler.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.io.Writer;
import java.util.Collection;
import java.util.List;
import javax.naming.SizeLimitExceededException;
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;
import net.yacy.cora.document.id.AnchorURL;
import net.yacy.document.parser.html.ContentScraper;
/**
* 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 OOXMLSpreeadsheetHandler extends DefaultHandler {
/** The entry name prefix of a data sheets in an OOXML container */
public static final String ENTRY_PREFIX = "xl/worksheets/sheet";
/** Name of a cell tag in a data sheet */
private static final String CELL_TAG = "c";
/** Attribute name indicating the type of a cell element in a data sheet */
private static final String CELL_TYPE_ATTRIBUTE = "t";
/** Name of a cell value tag in a data sheet */
private static final String CELL_VALUE_TAG = "v";
/**
* Cell type attribute value for a cell using a shared string
*
* @see "'Ecma Office Open XML Part 1 - Fundamentals And Markup Language Reference.pdf' - section 18.18.11 ST_CellType (Cell Type)"
*/
private static final String SHARED_STRING_CELL_TYPE = "s";
/** The document shared strings list */
private final List<String> sharedStrings;
/** Output writer for cells text */
private final Writer out;
/** Detected URLs */
private final Collection<AnchorURL> urls;
/** Maximum number of URLs to parse */
private final int maxURLs;
/** Number of parsed URLs in the data sheet */
private long detectedURLs;
/**
* Set to true when the last character written to the output writer is a space
*/
private boolean lastAppendedIsSpace;
/** Currently parsed cell value content. */
private StringBuilder cellValue;
/** Set to true when we are currently processing a XMl cell element */
private boolean inCell;
/** Set to true when we are currently processing a XML cell value element */
private boolean inCellValue;
/**
* Set to true when we are currently processing a XML cell element of Shared
* String type
*/
private boolean sharedStringCell;
/**
* @param sharedStrings
* the list of shared strings of the parent spredsheet document
* @param out
* the output writer to write text extracted from cells. Must not be
* null.
* @param urls
* the mutable collection of URLs to fill with detected URLs
* @throws IllegalArgumentException
* when out is null
*/
public OOXMLSpreeadsheetHandler(final List<String> sharedStrings, final Writer out,
final Collection<AnchorURL> urls) throws IllegalArgumentException {
this(sharedStrings, out, urls, Integer.MAX_VALUE);
}
/**
* @param out
* the output writer to write extracted text. Must not be null.
* @param urls
* the mutable collection of URLs to fill with detected URLs
* @param maxURLs
* the maximum number of urls to parse
* @throws IllegalArgumentException
* when out or urls parmeter is null
*/
public OOXMLSpreeadsheetHandler(final List<String> sharedStrings, final Writer out,
final Collection<AnchorURL> urls, final int maxURLs) throws IllegalArgumentException {
if (out == null) {
throw new IllegalArgumentException("out writer must not be null");
}
if (urls == null) {
throw new IllegalArgumentException("urls collection must not be null");
}
this.sharedStrings = sharedStrings;
this.out = out;
this.urls = urls;
this.maxURLs = maxURLs;
this.detectedURLs = 0;
this.lastAppendedIsSpace = false;
this.inCell = false;
this.inCellValue = false;
this.sharedStringCell = false;
}
/**
* @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.cellValue = new StringBuilder();
this.detectedURLs = 0;
this.lastAppendedIsSpace = false;
this.inCell = false;
this.inCellValue = false;
this.sharedStringCell = false;
}
@Override
public void startElement(final String uri, final String localName, final String qName, final Attributes attributes)
throws SAXException {
if (CELL_TAG.equals(qName)) {
this.cellValue.setLength(0);
this.inCell = true;
final String cellType = attributes.getValue(CELL_TYPE_ATTRIBUTE);
this.sharedStringCell = SHARED_STRING_CELL_TYPE.equals(cellType);
} else if (this.inCell && CELL_VALUE_TAG.equals(qName)) {
this.cellValue.setLength(0);
this.inCellValue = true;
}
}
/**
* 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 {
if (this.inCellValue) {
this.cellValue.append(ch, start, length);
}
}
/**
* Perform URLs detection on the ending element text
*
* @throws SAXException
* when the maxURLs limit has been reached
*/
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
if (CELL_VALUE_TAG.equals(qName)) {
String cellText = null;
if (this.sharedStringCell) {
/* Try to retrieve the cell text from the shared strings list */
try {
int index = Integer.parseInt(this.cellValue.toString());
if (this.sharedStrings != null && this.sharedStrings.size() > index) {
cellText = this.sharedStrings.get(index);
}
} catch (NumberFormatException ignored) {
/* Do not terminate parsing if one shared strings index value is malformed */
}
} else {
/* Use directly the cell value as text */
cellText = this.cellValue.toString();
}
try {
if (cellText != null && !cellText.isEmpty()) {
this.detectedURLs += ContentScraper.findAbsoluteURLs(cellText, this.urls, null,
this.maxURLs - this.detectedURLs);
/*
* Iif necessary we add a space to separate text content of different elements
*/
if (!this.lastAppendedIsSpace && !Character.isWhitespace(cellText.charAt(0))) {
this.out.write(" ");
}
this.out.write(cellText);
this.lastAppendedIsSpace = Character.isWhitespace(cellText.charAt(cellText.length() - 1));
}
} catch (IOException ioe) {
throw new SAXException("Error while appending characters to the output writer", ioe);
} finally {
this.cellValue.setLength(0);
this.inCellValue = false;
}
if (this.detectedURLs >= this.maxURLs) {
throw new SAXException(
new SizeLimitExceededException("Reached maximum URLs to parse : " + this.maxURLs));
}
} else if (CELL_TAG.equals(qName)) {
this.inCell = false;
this.inCellValue = false;
}
}
@Override
public void endDocument() throws SAXException {
/* Release the StringBuilder now useless */
this.cellValue = null;
}
}
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