Java tutorial
/* * $Id: PdfSmartCopy.java 3991 2009-06-18 21:21:09Z psoares33 $ * * Copyright 2007 Michael Neuweiler and Bruno Lowagie * * 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, 2000, 2001, 2002 by Bruno Lowagie. * All Rights Reserved. * Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer * are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved. * * This class was written by Michael Neuweiler based on hints given by Bruno Lowagie * * 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: * http://www.lowagie.com/iText/ */ package com.lowagie.text.pdf; import java.io.IOException; import java.io.OutputStream; import java.security.MessageDigest; import java.util.Arrays; import java.util.HashMap; import com.lowagie.text.Document; import com.lowagie.text.DocumentException; import com.lowagie.text.ExceptionConverter; /** * PdfSmartCopy has the same functionality as PdfCopy, * but when resources (such as fonts, images,...) are * encountered, a reference to these resources is saved * in a cache, so that they can be reused. * This requires more memory, but reduces the file size * of the resulting PDF document. */ public class PdfSmartCopy extends PdfCopy { /** the cache with the streams and references. */ private HashMap streamMap = null; /** Creates a PdfSmartCopy instance. */ public PdfSmartCopy(Document document, OutputStream os) throws DocumentException { super(document, os); this.streamMap = new HashMap(); } /** * Translate a PRIndirectReference to a PdfIndirectReference * In addition, translates the object numbers, and copies the * referenced object to the output file if it wasn't available * in the cache yet. If it's in the cache, the reference to * the already used stream is returned. * * NB: PRIndirectReferences (and PRIndirectObjects) really need to know what * file they came from, because each file has its own namespace. The translation * we do from their namespace to ours is *at best* heuristic, and guaranteed to * fail under some circumstances. */ protected PdfIndirectReference copyIndirect(PRIndirectReference in) throws IOException, BadPdfFormatException { PdfObject srcObj = PdfReader.getPdfObjectRelease(in); ByteStore streamKey = null; boolean validStream = false; if (srcObj.isStream()) { streamKey = new ByteStore((PRStream) srcObj); validStream = true; PdfIndirectReference streamRef = (PdfIndirectReference) streamMap.get(streamKey); if (streamRef != null) { return streamRef; } } PdfIndirectReference theRef; RefKey key = new RefKey(in); IndirectReferences iRef = (IndirectReferences) indirects.get(key); if (iRef != null) { theRef = iRef.getRef(); if (iRef.getCopied()) { return theRef; } } else { theRef = body.getPdfIndirectReference(); iRef = new IndirectReferences(theRef); indirects.put(key, iRef); } if (srcObj.isDictionary()) { PdfObject type = PdfReader.getPdfObjectRelease(((PdfDictionary) srcObj).get(PdfName.TYPE)); if (type != null && PdfName.PAGE.equals(type)) { return theRef; } } iRef.setCopied(); if (validStream) { streamMap.put(streamKey, theRef); } PdfObject obj = copyObject(srcObj); addToBody(obj, theRef); return theRef; } static class ByteStore { private byte[] b; private int hash; private MessageDigest md5; private void serObject(PdfObject obj, int level, ByteBuffer bb) throws IOException { if (level <= 0) return; if (obj == null) { bb.append("$Lnull"); return; } obj = PdfReader.getPdfObject(obj); if (obj.isStream()) { bb.append("$B"); serDic((PdfDictionary) obj, level - 1, bb); if (level > 0) { md5.reset(); bb.append(md5.digest(PdfReader.getStreamBytesRaw((PRStream) obj))); } } else if (obj.isDictionary()) { serDic((PdfDictionary) obj, level - 1, bb); } else if (obj.isArray()) { serArray((PdfArray) obj, level - 1, bb); } else if (obj.isString()) { bb.append("$S").append(obj.toString()); } else if (obj.isName()) { bb.append("$N").append(obj.toString()); } else bb.append("$L").append(obj.toString()); } private void serDic(PdfDictionary dic, int level, ByteBuffer bb) throws IOException { bb.append("$D"); if (level <= 0) return; Object[] keys = dic.getKeys().toArray(); Arrays.sort(keys); for (int k = 0; k < keys.length; ++k) { serObject((PdfObject) keys[k], level, bb); serObject(dic.get((PdfName) keys[k]), level, bb); } } private void serArray(PdfArray array, int level, ByteBuffer bb) throws IOException { bb.append("$A"); if (level <= 0) return; for (int k = 0; k < array.size(); ++k) { serObject(array.getPdfObject(k), level, bb); } } ByteStore(PRStream str) throws IOException { try { md5 = MessageDigest.getInstance("MD5"); } catch (Exception e) { throw new ExceptionConverter(e); } ByteBuffer bb = new ByteBuffer(); int level = 100; serObject(str, level, bb); this.b = bb.toByteArray(); md5 = null; } public boolean equals(Object obj) { if (!(obj instanceof ByteStore)) return false; if (hashCode() != obj.hashCode()) return false; return Arrays.equals(b, ((ByteStore) obj).b); } public int hashCode() { if (hash == 0) { int len = b.length; for (int k = 0; k < len; ++k) { hash = hash * 31 + (b[k] & 0xff); } } return hash; } } }