Java tutorial
/* * $Id$ */ /* Copyright (c) 2000-2016 Board of Trustees of Leland Stanford Jr. University, all rights reserved. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL STANFORD UNIVERSITY BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. Except as contained in this notice, the name of Stanford University shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from Stanford University. */ package org.lockss.pdf.pdfbox; import java.io.*; import java.util.*; import org.apache.pdfbox.cos.*; import org.apache.pdfbox.pdmodel.*; import org.apache.pdfbox.pdmodel.graphics.xobject.*; import org.lockss.pdf.*; import org.lockss.util.Logger; /** * <p> * A {@link PdfPage} implementation based on PDFBox 1.6.0. * </p> * <p> * This class acts as an adapter for the {@link PDPage} class. * </p> * * @author Thib Guicherd-Callin * @since 1.56 * @see PdfBoxDocumentFactory */ public class PdfBoxPage implements PdfPage { /** * <p> * Logger for use by this class. * </p> * * @since 1.56 */ private static final Logger log = Logger.getLogger(PdfBoxPage.class); /** * <p> * Returns an XObject from the given resources, as a {@link PDXObject} * instance. * </p> * * @param pdResources * A {@link PDResources} instance. * @param name * The name of the desired XObject. * @return The requested XObject, or <code>null</code> if not found. * @throws PdfException * If PDF processing fails. * @since 1.61 */ protected static PDXObject getPDXObjectByName(PDResources pdResources, String name) throws PdfException { /* * IMPLEMENTATION NOTE * * This map contains objects of type PDXObject (PDFBox 1.6.0: * see PDResources lines 157 and 160), which are null, or of * type either PDXObjectForm (see PDXObject line 162) or PDJpeg * (line 140) or PDCcitt (line 144) or PDPixelMap (line 153). * The latter three have a common supertype, PDXObjectImage. */ return (PDXObject) (pdResources.getXObjects().get(name)); } /** * <p> * Determines if the given {@link PDXObject} instance is a byte * stream (as opposed to a token stream). * </p> * * @param xObject A {@link PDXObject} instance. * @return <code>true</code> if and only if the argument is a byte * stream. * @since 1.56.3 * @see #isTokenStream(PDXObject) */ private static boolean isByteStream(PDXObject xObject) { return !isTokenStream(xObject); } /** * <p> * Determines if the given {@link PDXObject} instance is a token * stream (as opposed to a byte stream). * </p> * * @param xObject A {@link PDXObject} instance. * @return <code>true</code> if and only if the argument is a token * stream. * @since 1.56.3 */ private static boolean isTokenStream(PDXObject xObject) { /* * IMPLEMENTATION NOTE * * PDXObject is an abstract class whose subtypes all represent * image XObjects (PDJpeg, PDCcitt or PDPixelMap) i.e. a byte * stream, except one, PDXObjectForm, which represents a form * XObject i.e. a token stream. */ return xObject instanceof PDXObjectForm; } /** * <p> * The parent {@link PdfBoxDocument} instance. * </p> * * @since 1.56 */ protected final PdfBoxDocument pdfBoxDocument; /** * <p> * The {@link PDPage) instance this instance represents. * </p> * * @since 1.56 */ protected final PDPage pdPage; /** * <p> * Constructor. * </p> * * @param pdfBoxDocument The parent {@link PdfBoxDocument} instance. * @param pdPage The {@link PDPage} instance underpinning this PDF * page. * @since 1.56 */ public PdfBoxPage(PdfBoxDocument pdfBoxDocument, PDPage pdPage) { this.pdfBoxDocument = pdfBoxDocument; this.pdPage = pdPage; } @Override public List<InputStream> getAllByteStreams() throws PdfException { List<InputStream> ret = new ArrayList<InputStream>(); PdfTokenStream pageTokenStream = getPageTokenStream(); // Use findResources(), not getResources() (inspired by getAllTokenStreams() below) recursivelyFindByteStreams(pageTokenStream, pdPage.findResources(), ret); return ret; } @Override public List<PdfTokenStream> getAllTokenStreams() throws PdfException { List<PdfTokenStream> ret = new ArrayList<PdfTokenStream>(); PdfTokenStream pageTokenStream = getPageTokenStream(); ret.add(pageTokenStream); // Use findResources(), not getResources() (e.g. PDFBox 1.8.7 PDFTextStripper.java line 460) recursivelyFindTokenStreams(pageTokenStream, pdPage.findResources(), ret); return ret; } @Override public List<PdfToken> getAnnotations() { /* * IMPLEMENTATION NOTE * * Annotations are just dictionaries, but because there are many * types, the PDFBox API defines a vast hierarchy of objects to * represent them. At this time, this is way too much detail for * this API, because only one type of annotation has a foreseeable * use case (the Link type). So for now, we are only representing * annotations as the dictionaries they are by circumventing the * PDAnnotation factory call in getAnnotations() (PDFBox 1.6.0: * PDPage line 780). */ COSDictionary pageDictionary = pdPage.getCOSDictionary(); COSArray annots = (COSArray) pageDictionary.getDictionaryObject(COSName.ANNOTS); if (annots == null) { return new ArrayList<PdfToken>(); } return PdfBoxTokens.getArray(annots); } @Override public PdfBoxDocument getDocument() { return pdfBoxDocument; } @Override public PdfTokenStream getPageTokenStream() throws PdfException { try { return getDocument().getDocumentFactory().makePageTokenStream(this, pdPage.getContents()); } catch (IOException ioe) { throw new PdfException("Failed to get the page content stream", ioe); } } @Override public void setAnnotations(List<PdfToken> annotations) { pdPage.getCOSDictionary().setItem(COSName.ANNOTS, PdfBoxTokens.asCOSArray(annotations)); } /** * <p> * Traverses the given token stream (and associated resources object), adding * any embedded image data to the given list, and recursively traversing any * referenced XObject streams. * </p> * * @param pdfTokenStream * A token stream. * @param pdResources * The token stream's resources object, * @param ret * A list into which byte streams are appended. * @throws PdfException * If PDF processing fails. * @since 1.61 */ private void recursivelyFindByteStreams(PdfTokenStream pdfTokenStream, final PDResources pdResources, final List<InputStream> ret) throws PdfException { PdfTokenStreamWorker worker = new PdfTokenStreamWorker() { @Override public void operatorCallback() throws PdfException { // 'ID' and 'BI' if (isBeginImageData() || isBeginImageObject()) { /* * IMPLEMENTATION NOTE * * getImageData() (PDFBox 1.6.0: PDFOperator line 105) does * not copy the byte array, nor does ByteArrayInputStream * (http://docs.oracle.com/javase/1.5.0/docs/api/java/io/ByteArrayInputStream.html#ByteArrayInputStream%28byte[]%29). */ ret.add(new ByteArrayInputStream(PdfBoxTokens.asPDFOperator(getOperator()).getImageData())); } // 'Do' else if (isInvokeXObject()) { PdfToken operand = getTokens().get(getIndex() - 1); if (operand.isName()) { PDXObject xObject = getPDXObjectByName(pdResources, operand.getName()); if (isByteStream(xObject)) { try { ret.add(xObject.getCOSStream().getUnfilteredStream()); } catch (IOException ioe) { log.debug2("recursivelyFindByteStreams: Error retrieving a byte stream", ioe); } } else { PDXObjectForm pdxObjectForm = (PDXObjectForm) xObject; PdfBoxXObjectTokenStream referencedTokenStream = getDocument().getDocumentFactory() .makeXObjectTokenStream(PdfBoxPage.this, Arrays.asList(pdxObjectForm, pdResources, pdxObjectForm.getResources())); recursivelyFindByteStreams(referencedTokenStream, referencedTokenStream.getStreamResources(), // pdxObjectForm.getResources() or pdResources if null ret); } } else { log.debug2("recursivelyFindByteStreams: invalid input"); } } } }; worker.process(pdfTokenStream); } /** * <p> * Traverses the given token stream (and associated resources object), adding * any embedded XObject streams to the given list, and recursively traversing * them. Note that the given stream itself is not appended to the list. * </p> * * @param pdfTokenStream * A token stream. * @param pdResources * The token stream's resources object, * @param ret * A list into which byte streams are appended. * @throws PdfException * If PDF processing fails. * @since 1.61 */ private void recursivelyFindTokenStreams(PdfTokenStream pdfTokenStream, final PDResources pdResources, final List<PdfTokenStream> ret) throws PdfException { PdfTokenStreamWorker worker = new PdfTokenStreamWorker() { @Override public void operatorCallback() throws PdfException { if (isInvokeXObject()) { PdfToken operand = getTokens().get(getIndex() - 1); if (operand.isName()) { PDXObject xObject = getPDXObjectByName(pdResources, operand.getName()); if (isTokenStream(xObject)) { PDXObjectForm pdxObjectForm = (PDXObjectForm) xObject; PdfBoxXObjectTokenStream referencedTokenStream = getDocument().getDocumentFactory() .makeXObjectTokenStream(PdfBoxPage.this, Arrays.asList(pdxObjectForm, pdResources, pdxObjectForm.getResources())); ret.add(referencedTokenStream); recursivelyFindTokenStreams(referencedTokenStream, referencedTokenStream.getStreamResources(), // pdxObjectForm.getResources() or pdResources if null ret); } } else { log.debug2("recursivelyFindTokenStreams: invalid input"); } } } }; worker.process(pdfTokenStream); } }