itextpdf.jar is a component in iText 5 Java library to provide core functionalities. iText Java library allows you to generate and manage PDF documents.

The Source Code files are provided at iText GitHub site.

You can compile it to generate your JAR file, using pom.xml as the build configuration file.

The source code of itextpdf-5.5.14.jar is provided below:

⏎ com/itextpdf/text/pdf/PdfSmartCopy.java

/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
 * Authors: Bruno Lowagie, Paulo Soares, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS
 *
 * 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 Affero General Public License for more details.
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License,
 * a covered work must retain the producer line in every PDF that is created
 * or manipulated using iText.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the iText software without
 * disclosing the source code of your own applications.
 * These activities include: offering paid services to customers as an ASP,
 * serving PDFs on the fly in a web application, shipping iText with a closed
 * source product.
 *
 * For more information, please contact iText Software Corp. at this
 * address: sales@itextpdf.com
 */
package com.itextpdf.text.pdf;

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.ExceptionConverter;
import com.itextpdf.text.error_messages.MessageLocalization;
import com.itextpdf.text.log.Counter;
import com.itextpdf.text.log.CounterFactory;
import com.itextpdf.text.log.Logger;
import com.itextpdf.text.log.LoggerFactory;

import java.io.IOException;
import java.io.OutputStream;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.HashMap;

/**
 * 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 {

    private static final Logger LOGGER = LoggerFactory.getLogger(PdfSmartCopy.class);

	/** the cache with the streams and references. */
    private HashMap<ByteStore, PdfIndirectReference> streamMap = null;
    private final HashMap<RefKey, Integer> serialized = new HashMap<RefKey, Integer>();

    protected Counter COUNTER = CounterFactory.getCounter(PdfSmartCopy.class);
    protected Counter getCounter() {
    	return COUNTER;
    }

    /** Creates a PdfSmartCopy instance. */
    public PdfSmartCopy(Document document, OutputStream os) throws DocumentException {
        super(document, os);
        this.streamMap = new HashMap<ByteStore, PdfIndirectReference>();
    }
    /**
     * 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.
     */
    @Override
    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, serialized);
            validStream = true;
            PdfIndirectReference streamRef = streamMap.get(streamKey);
            if (streamRef != null) {
                return streamRef;
            }
        }
        else if (srcObj.isDictionary()) {
            streamKey = new ByteStore((PdfDictionary)srcObj, serialized);
            validStream = true;
            PdfIndirectReference streamRef = streamMap.get(streamKey);
            if (streamRef != null) {
                return streamRef;
            }
        }

        PdfIndirectReference theRef;
        RefKey key = new RefKey(in);
        IndirectReferences iRef = 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) {
                if ((PdfName.PAGE.equals(type))) {
                    return theRef;
                }
                if ((PdfName.CATALOG.equals(type))) {
                    LOGGER.warn(MessageLocalization.getComposedMessage("make.copy.of.catalog.dictionary.is.forbidden"));
                    return null;
                }
            }
        }
        iRef.setCopied();

        if (validStream) {
            streamMap.put(streamKey, theRef);
        }

        PdfObject obj = copyObject(srcObj);
        addToBody(obj, theRef);
        return theRef;
    }

    @Override
    public void freeReader(PdfReader reader) throws IOException {
        serialized.clear();
        super.freeReader(reader);
    }

    @Override
    public void addPage(PdfImportedPage iPage) throws IOException, BadPdfFormatException {
        if (currentPdfReaderInstance.getReader() != reader)
            serialized.clear();
        super.addPage(iPage);
    }

    static class ByteStore {
        private final byte[] b;
        private final int hash;
        private MessageDigest md5;

        private void serObject(PdfObject obj, int level, ByteBuffer bb, HashMap<RefKey, Integer> serialized) throws IOException {
            if (level <= 0)
                return;
            if (obj == null) {
                bb.append("$Lnull");
                return;
            }
            PdfIndirectReference ref = null;
            ByteBuffer savedBb = null;

            if (obj.isIndirect()) {
                ref = (PdfIndirectReference)obj;
                RefKey key = new RefKey(ref);
                if (serialized.containsKey(key)) {
                    bb.append(serialized.get(key));
                    return;
                }
                else {
                    savedBb = bb;
                    bb = new ByteBuffer();
                }
            }
            obj = PdfReader.getPdfObject(obj);
            if (obj.isStream()) {
                bb.append("$B");
                serDic((PdfDictionary) obj, level - 1, bb, serialized);
                if (level > 0) {
                    md5.reset();
                    bb.append(md5.digest(PdfReader.getStreamBytesRaw((PRStream)obj)));
                }
            }
            else if (obj.isDictionary()) {
                serDic((PdfDictionary)obj, level - 1, bb, serialized);
            }
            else if (obj.isArray()) {
                serArray((PdfArray)obj, level - 1, bb, serialized);
            }
            else if (obj.isString()) {
                bb.append("$S").append(obj.toString());
            }
            else if (obj.isName()) {
                bb.append("$N").append(obj.toString());
            }
            else
                bb.append("$L").append(obj.toString());

            if (savedBb != null) {
                RefKey key = new RefKey(ref);
                if (!serialized.containsKey(key))
                    serialized.put(key, calculateHash(bb.getBuffer()));
                savedBb.append(bb);
            }
        }

        private void serDic(PdfDictionary dic, int level, ByteBuffer bb, HashMap<RefKey, Integer> serialized) 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) {
                if(keys[k].equals(PdfName.P) &&(dic.get((PdfName)keys[k]).isIndirect() || dic.get((PdfName)keys[k]).isDictionary())) // ignore recursive call
                    continue;
                    serObject((PdfObject) keys[k], level, bb, serialized);
                    serObject(dic.get((PdfName) keys[k]), level, bb, serialized);

            }
        }

        private void serArray(PdfArray array, int level, ByteBuffer bb, HashMap<RefKey, Integer> serialized) throws IOException {
            bb.append("$A");
            if (level <= 0)
                return;
            for (int k = 0; k < array.size(); ++k) {
                serObject(array.getPdfObject(k), level, bb, serialized);
            }
        }

        ByteStore(PRStream str, HashMap<RefKey, Integer> serialized) 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, serialized);
            this.b = bb.toByteArray();
            hash = calculateHash(this.b);
            md5 = null;
        }

        ByteStore(PdfDictionary dict, HashMap<RefKey, Integer> serialized) throws IOException {
            try {
                md5 = MessageDigest.getInstance("MD5");
            }
            catch (Exception e) {
                throw new ExceptionConverter(e);
            }
            ByteBuffer bb = new ByteBuffer();
            int level = 100;
            serObject(dict, level, bb, serialized);
            this.b = bb.toByteArray();
            hash = calculateHash(this.b);
            md5 = null;
        }

        private static int calculateHash(byte[] b) {
             int hash = 0;
                int len = b.length;
                for (int k = 0; k < len; ++k)
                    hash = hash * 31 + (b[k] & 0xff);
             return hash;
        }

        @Override
        public boolean equals(Object obj) {
            if (!(obj instanceof ByteStore))
                return false;
            if (hashCode() != obj.hashCode())
                return false;
            return Arrays.equals(b, ((ByteStore)obj).b);
        }

        @Override
        public int hashCode() {
            return hash;
        }
    }
}

⏎ com/itextpdf/text/pdf/PdfSmartCopy.java

Or download all of them as a single archive file:

File name: itextpdf-5.5.14-fyi.zip
File size: 2163839 bytes
Release date: 2009-10-09
Download 

⇒ iText-2.1.6.jar - iText, a JAVA-PDF library

⇐ iText layout.jar Source Code

⇑ Download and Install iText Java Library

⇑⇑ iText for PDF Generation