Java tutorial
/***************************************************************************** * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. * ****************************************************************************/ package org.apache.padaf.preflight.helpers; import java.io.IOException; import java.util.ArrayList; import java.util.List; import org.apache.padaf.preflight.DocumentHandler; import org.apache.padaf.preflight.ValidationConstants; import org.apache.padaf.preflight.ValidationException; import org.apache.padaf.preflight.ValidationResult; import org.apache.padaf.preflight.ValidatorConfig; import org.apache.padaf.preflight.ValidationResult.ValidationError; import org.apache.padaf.preflight.utils.COSUtils; import org.apache.padaf.preflight.utils.PdfElementParser; import org.apache.pdfbox.cos.COSArray; import org.apache.pdfbox.cos.COSBase; import org.apache.pdfbox.cos.COSDictionary; import org.apache.pdfbox.cos.COSDocument; import org.apache.pdfbox.cos.COSName; import org.apache.pdfbox.cos.COSObject; import org.apache.pdfbox.cos.COSString; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.persistence.util.COSObjectKey; /** * @author eric * */ public class TrailerValidationHelper extends AbstractValidationHelper { public TrailerValidationHelper(ValidatorConfig cfg) throws ValidationException { super(cfg); } /* * (non-Javadoc) * * @see * net.awl.edoc.pdfa.validation.helpers.AbstractValidationHelper#validate( * net.awl.edoc.pdfa.validation.DocumentHandler) */ @Override public List<ValidationError> innerValidate(DocumentHandler handler) throws ValidationException { List<ValidationError> result = new ArrayList<ValidationError>(0); PDDocument pdfDoc = handler.getDocument(); COSDictionary linearizedDict = isLinearizedPdf(pdfDoc); if (linearizedDict != null) { // it is a linearized PDF, check the linearized dictionary checkLinearizedDictionnary(linearizedDict, result); // if the pdf is a linearized pdf. the first trailer must be checked // and it must have the same ID than the last trailer. // According to the PDF version, trailers are available by the trailer key word (pdf <= 1.4) // or in the dictionary of the XRef stream ( PDF >= 1.5) String pdfVersion = pdfDoc.getDocument().getHeaderString(); if (pdfVersion != null && pdfVersion.matches("%PDF-1\\.[1-4]")) { checkTrailersForLinearizedPDF14(handler, result); } else { checkTrailersForLinearizedPDF15(handler, result); } } else { // If the PDF isn't a linearized one, only the last trailer must be checked checkMainTrailer(pdfDoc.getDocument(), pdfDoc.getDocument().getTrailer(), result); } return result; } /** * Extracts and compares first and last trailers for PDF version between 1.1 and 1.4 * @param handler * @param result */ protected void checkTrailersForLinearizedPDF14(DocumentHandler handler, List<ValidationError> result) { PDDocument pdfDoc = handler.getDocument(); List<String> lTrailers = handler.getPdfExtractor().getAllTrailers(); if (lTrailers.isEmpty()) { result.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER, "There are no trailer in the PDF file")); } else { String firstTrailer = lTrailers.get(0); String lastTrailer = lTrailers.get(lTrailers.size() - 1); COSDictionary first = null; COSDictionary last = null; COSDocument cd = null; try { cd = new COSDocument(); PdfElementParser parser1 = new PdfElementParser(cd, firstTrailer.getBytes()); first = parser1.parseAsDictionary(); PdfElementParser parser2 = new PdfElementParser(cd, lastTrailer.getBytes()); last = parser2.parseAsDictionary(); checkMainTrailer(pdfDoc.getDocument(), first, result); if (!compareIds(first, last, pdfDoc.getDocument())) { result.add(new ValidationResult.ValidationError( ValidationConstants.ERROR_SYNTAX_TRAILER_ID_CONSISTENCY, "ID is different in the first and the last trailer")); } } catch (IOException e) { result.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER, "Unable to parse trailers of the linearized PDF")); } finally { COSUtils.closeDocumentQuietly(cd); } } } /** * Accesses and compares First and Last trailers for a PDF version higher than 1.4. * * @param handler * @param result */ protected void checkTrailersForLinearizedPDF15(DocumentHandler handler, List<ValidationError> result) { PDDocument pdfDoc = handler.getDocument(); try { COSDocument cosDocument = pdfDoc.getDocument(); List<COSObject> xrefs = cosDocument.getObjectsByType(COSName.XREF); if (xrefs.isEmpty()) { // no XRef CosObject, may by this pdf file used the PDF 1.4 syntaxe checkTrailersForLinearizedPDF14(handler, result); } else { long min = Long.MAX_VALUE; long max = Long.MIN_VALUE; COSDictionary firstTrailer = null; COSDictionary lastTrailer = null; // Search First and Last trailers according to offset position. for (COSObject co : xrefs) { long offset = cosDocument.getXrefTable().get(new COSObjectKey(co)); if (offset < min) { min = offset; firstTrailer = (COSDictionary) co.getObject(); } if (offset > max) { max = offset; lastTrailer = (COSDictionary) co.getObject(); } } checkMainTrailer(pdfDoc.getDocument(), firstTrailer, result); if (!compareIds(firstTrailer, lastTrailer, pdfDoc.getDocument())) { result.add(new ValidationResult.ValidationError( ValidationConstants.ERROR_SYNTAX_TRAILER_ID_CONSISTENCY, "ID is different in the first and the last trailer")); } } } catch (IOException e) { result.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER, "Unable to check PDF Trailers due to : " + e.getMessage())); } } /** * Return true if the ID of the first dictionary is the same as the id of the * last dictionary Return false otherwise. * * @param first * @param last * @return */ protected boolean compareIds(COSDictionary first, COSDictionary last, COSDocument doc) { COSBase idFirst = first.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_ID)); COSBase idLast = last.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_ID)); if (idFirst == null || idLast == null) { return false; } // ---- cast two COSBase to COSArray. COSArray af = COSUtils.getAsArray(idFirst, doc); COSArray al = COSUtils.getAsArray(idLast, doc); // ---- if one COSArray is null, the PDF/A isn't valid if ((af == null) || (al == null)) { return false; } // ---- compare both arrays boolean isEqual = true; for (Object of : af.toList()) { boolean oneIsEquals = false; for (Object ol : al.toList()) { // ---- according to PDF Reference 1-4, ID is an array containing two // strings if (!oneIsEquals) oneIsEquals = ((COSString) ol).getString().equals(((COSString) of).getString()); } isEqual = isEqual && oneIsEquals; } return isEqual; } /** * check if all keys are authorized in a trailer dictionary and if the type is * valid. * * @param trailer * @param lErrors */ protected void checkMainTrailer(COSDocument doc, COSDictionary trailer, List<ValidationError> lErrors) { boolean id = false; boolean root = false; boolean size = false; boolean prev = false; boolean info = false; boolean encrypt = false; for (Object key : trailer.keySet()) { if (!(key instanceof COSName)) { lErrors.add(new ValidationResult.ValidationError( ValidationConstants.ERROR_SYNTAX_DICTIONARY_KEY_INVALID, "Invalid key in The trailer dictionary")); return; } String cosName = ((COSName) key).getName(); if (cosName.equals(TRAILER_DICTIONARY_KEY_ENCRYPT)) { encrypt = true; } if (cosName.equals(TRAILER_DICTIONARY_KEY_SIZE)) { size = true; } if (cosName.equals(TRAILER_DICTIONARY_KEY_PREV)) { prev = true; } if (cosName.equals(TRAILER_DICTIONARY_KEY_ROOT)) { root = true; } if (cosName.equals(TRAILER_DICTIONARY_KEY_INFO)) { info = true; } if (cosName.equals(TRAILER_DICTIONARY_KEY_ID)) { id = true; } } // ---- PDF/A Trailer dictionary must contain the ID key if (!id) { lErrors.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_MISSING_ID, "The trailer dictionary doesn't contain ID")); } else { COSBase trailerId = trailer.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_ID)); if (!COSUtils.isArray(trailerId, doc)) { lErrors.add( new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_TYPE_INVALID, "The trailer dictionary contains an id but it isn't an array")); } } // ---- PDF/A Trailer dictionary mustn't contain the Encrypt key if (encrypt) { lErrors.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_ENCRYPT, "The trailer dictionary contains Encrypt")); } // ---- PDF Trailer dictionary must contain the Size key if (!size) { lErrors.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_MISSING_SIZE, "The trailer dictionary doesn't contain Size")); } else { COSBase trailerSize = trailer.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_SIZE)); if (!COSUtils.isInteger(trailerSize, doc)) { lErrors.add( new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_TYPE_INVALID, "The trailer dictionary contains a size but it isn't an integer")); } } // ---- PDF Trailer dictionary must contain the Root key if (!root) { lErrors.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_MISSING_ROOT, "The trailer dictionary doesn't contain Root")); } else { COSBase trailerRoot = trailer.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_ROOT)); if (!COSUtils.isDictionary(trailerRoot, doc)) { lErrors.add( new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_TYPE_INVALID, "The trailer dictionary contains a root but it isn't a dictionary")); } } // ---- PDF Trailer dictionary may contain the Prev key if (prev) { COSBase trailerPrev = trailer.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_PREV)); if (!COSUtils.isInteger(trailerPrev, doc)) { lErrors.add( new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_TYPE_INVALID, "The trailer dictionary contains a prev but it isn't an integer")); } } // ---- PDF Trailer dictionary may contain the Info key if (info) { COSBase trailerInfo = trailer.getItem(COSName.getPDFName(TRAILER_DICTIONARY_KEY_INFO)); if (!COSUtils.isDictionary(trailerInfo, doc)) { lErrors.add( new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_TRAILER_TYPE_INVALID, "The trailer dictionary contains an info but it isn't a dictionary")); } } } /** * According to the PDF Reference, A linearized PDF contain a dictionary as * first object (linearized dictionary) and only this one in the first * section. * * @param document * @return */ protected COSDictionary isLinearizedPdf(PDDocument document) { // ---- Get Ref to obj COSDocument cDoc = document.getDocument(); List<?> lObj = cDoc.getObjects(); for (Object object : lObj) { COSBase curObj = ((COSObject) object).getObject(); if (curObj instanceof COSDictionary && ((COSDictionary) curObj).keySet().contains(COSName.getPDFName(DICTIONARY_KEY_LINEARIZED))) { return (COSDictionary) curObj; } } return null; } /** * Check if mandatory keys of linearized dictionary are present. * * @param lErrors */ protected void checkLinearizedDictionnary(COSDictionary linearizedDict, List<ValidationError> lErrors) { // ---- check if all keys are authorized in a linearized dictionary // ---- Linearized dictionary must contain the lhoent keys boolean l = false; boolean h = false; boolean o = false; boolean e = false; boolean n = false; boolean t = false; for (Object key : linearizedDict.keySet()) { if (!(key instanceof COSName)) { lErrors.add(new ValidationResult.ValidationError( ValidationConstants.ERROR_SYNTAX_DICTIONARY_KEY_INVALID, "Invalid key in The Linearized dictionary")); return; } String cosName = ((COSName) key).getName(); if (cosName.equals(DICTIONARY_KEY_LINEARIZED_L)) { l = true; } if (cosName.equals(DICTIONARY_KEY_LINEARIZED_H)) { h = true; } if (cosName.equals(DICTIONARY_KEY_LINEARIZED_O)) { o = true; } if (cosName.equals(DICTIONARY_KEY_LINEARIZED_E)) { e = true; } if (cosName.equals(DICTIONARY_KEY_LINEARIZED_N)) { n = true; } if (cosName.equals(DICTIONARY_KEY_LINEARIZED_T)) { t = true; } } if (!(l && h && o && e && t && n)) { lErrors.add(new ValidationResult.ValidationError(ValidationConstants.ERROR_SYNTAX_DICT_INVALID, "Invalid key in The Linearized dictionary")); } return; } }