com.lowagie.text.pdf.parser.PdfTextExtractor Maven / Gradle / Ivy
/*
* Copyright 2008 by Kevin Day.
*
* Contributions copyright 2014 Tizra Inc.
*
* The contents of this file are subject to the Mozilla Public License Version 1.1
* (the "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the License.
*
* The Original Code is 'iText, a free JAVA-PDF library'.
*
* The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
* the Initial Developer are Copyright (C) 1999-2008 by Bruno Lowagie.
* All Rights Reserved.
* Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
* are Copyright (C) 2000-2008 by Paulo Soares. All Rights Reserved.
*
* Contributor(s): all the names of the contributors are added in the source code
* where applicable.
*
* Alternatively, the contents of this file may be used under the terms of the
* LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
* provisions of LGPL are applicable instead of those above. If you wish to
* allow use of your version of this file only under the terms of the LGPL
* License and not to allow others to use your version of this file under
* the MPL, indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by the LGPL.
* If you do not delete the provisions above, a recipient may use your version
* of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the MPL as stated above or under the terms of the GNU
* Library General Public License as published by the Free Software Foundation;
* either version 2 of the License, or any later version.
*
* This library 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 Library general Public License for more
* details.
*
* If you didn't download this code from the following link, you should check if
* you aren't using an obsolete version:
* https://github.com/LibrePDF/OpenPDF
*/
package com.lowagie.text.pdf.parser;
import com.lowagie.text.ExceptionConverter;
import com.lowagie.text.pdf.PRIndirectReference;
import com.lowagie.text.pdf.PRStream;
import com.lowagie.text.pdf.PRTokeniser;
import com.lowagie.text.pdf.PdfArray;
import com.lowagie.text.pdf.PdfContentParser;
import com.lowagie.text.pdf.PdfDictionary;
import com.lowagie.text.pdf.PdfLiteral;
import com.lowagie.text.pdf.PdfName;
import com.lowagie.text.pdf.PdfObject;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.RandomAccessFileOrArray;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Extracts text from a PDF file.
*
* @since 2.1.4
*/
@SuppressWarnings("WeakerAccess")
public class PdfTextExtractor {
/**
* The PdfReader that holds the PDF file.
*/
private final PdfReader reader;
/**
* The {@link TextAssembler} that will receive render notifications and
* provide resultant text
*/
private final TextAssembler renderListener;
/**
* Creates a new Text Extractor object, using a {@link TextAssembler} as the
* render listener
*
* @param reader the reader with the PDF
*/
public PdfTextExtractor(PdfReader reader) {
this(reader, new MarkedUpTextAssembler(reader));
}
/**
* Creates a new Text Extractor object, using a {@link TextAssembler} as the
* render listener
*
* @param reader the reader with the PDF
* @param usePdfMarkupElements should we use higher level tags for PDF markup entities?
*/
public PdfTextExtractor(PdfReader reader, boolean usePdfMarkupElements) {
this(reader, new MarkedUpTextAssembler(reader, usePdfMarkupElements));
}
/**
* Creates a new Text Extractor object.
*
* @param reader the reader with the PDF
* @param renderListener the render listener that will be used to analyze renderText
* operations and provide resultant text
*/
public PdfTextExtractor(PdfReader reader, TextAssembler renderListener) {
this.reader = reader;
this.renderListener = renderListener;
}
/**
* Gets the content bytes of a page.
*
* @param pageNum the 1-based page number of page you want get the content
* stream from
* @return a byte array with the effective content stream of a page
* @throws IOException
*/
private byte[] getContentBytesForPage(int pageNum) throws IOException {
try (RandomAccessFileOrArray ignored = reader.getSafeFile()) {
PdfDictionary pageDictionary = reader.getPageN(pageNum);
PdfObject contentObject = pageDictionary.get(PdfName.CONTENTS);
return getContentBytesFromContentObject(contentObject);
}
}
/**
* Gets the content bytes from a content object, which may be a reference a
* stream or an array.
*
* @param contentObject the object to read bytes from
* @return the content bytes
* @throws IOException
*/
private byte[] getContentBytesFromContentObject(PdfObject contentObject) throws IOException {
final byte[] result;
switch (contentObject.type()) {
case PdfObject.INDIRECT:
PRIndirectReference ref = (PRIndirectReference) contentObject;
PdfObject directObject = PdfReader.getPdfObject(ref);
result = getContentBytesFromContentObject(directObject);
break;
case PdfObject.STREAM:
PRStream stream = (PRStream) PdfReader.getPdfObject(contentObject);
result = PdfReader.getStreamBytes(stream);
break;
case PdfObject.ARRAY:
// Stitch together all content before calling processContent(),
// because
// processContent() resets state.
ByteArrayOutputStream allBytes = new ByteArrayOutputStream();
PdfArray contentArray = (PdfArray) contentObject;
for (PdfObject pdfObject : contentArray.getElements()) {
allBytes.write(getContentBytesFromContentObject(pdfObject));
}
result = allBytes.toByteArray();
break;
default:
throw new IllegalStateException("Unable to handle Content of type " + contentObject.getClass());
}
return result;
}
/**
* Gets the text from a page.
*
* @param page the 1-based page number of page
* @return a String with the content as plain text (without PDF syntax)
* @throws IOException on error
*/
public String getTextFromPage(int page) throws IOException {
return getTextFromPage(page, false);
}
/**
* get the text from the page
*
* @param page page number we are interested in
* @param useContainerMarkup should we put tags in for PDf markup container elements (not
* really HTML at the moment).
* @return result of extracting the text, with tags as requested.
* @throws IOException on error
*/
public String getTextFromPage(int page, boolean useContainerMarkup) throws IOException {
PdfDictionary pageDict = reader.getPageN(page);
if (pageDict == null) {
return "";
}
PdfDictionary resources = pageDict.getAsDict(PdfName.RESOURCES);
renderListener.reset();
renderListener.setPage(page);
PdfContentStreamHandler handler = new PdfContentStreamHandler(renderListener);
processContent(getContentBytesForPage(page), resources, handler);
return handler.getResultantText();
}
/**
* Processes PDF syntax
*
* @param contentBytes the bytes of a content stream
* @param resources the resources that come with the content stream
* @param handler interprets events caused by recognition of operations in a
* content stream.
*/
public void processContent(byte[] contentBytes, PdfDictionary resources,
PdfContentStreamHandler handler) {
handler.pushContext("div class='t-extracted-page'");
try {
PdfContentParser ps = new PdfContentParser(new PRTokeniser(contentBytes));
List operands = new ArrayList<>();
while (ps.parse(operands).size() > 0) {
PdfLiteral operator = (PdfLiteral) operands.get(operands.size() - 1);
handler.invokeOperator(operator, operands, resources);
}
} catch (Exception e) {
throw new ExceptionConverter(e);
}
handler.popContext();
}
}