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/PdfConcatenate.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 java.io.IOException;
import java.io.OutputStream;

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;

/**
 * Wrapper class for PdfCopy and PdfSmartCopy.
 * Allows you to concatenate existing PDF documents with much less code.
 */
public class PdfConcatenate {
	/** The Document object for PdfCopy. */
	protected Document document;
	/** The actual PdfWriter */
	protected PdfCopy copy;
	
	/**
	 * Creates an instance of the concatenation class.
	 * @param os	the OutputStream for the PDF document
	 */
	public PdfConcatenate(OutputStream os) throws DocumentException {
		this(os, false);
	}

	/**
	 * Creates an instance of the concatenation class.
	 * @param os	the OutputStream for the PDF document
	 * @param smart	do we want PdfCopy to detect redundant content?
	 */
	public PdfConcatenate(OutputStream os, boolean smart) throws DocumentException {
		document = new Document();
		if (smart)
			copy = new PdfSmartCopy(document, os);
		else
			copy = new PdfCopy(document, os);	
	}
	
	/**
	 * Adds the pages from an existing PDF document.
	 * @param reader	the reader for the existing PDF document
	 * @return			the number of pages that were added
	 * @throws DocumentException
	 * @throws IOException
	 */
	public int addPages(PdfReader reader) throws DocumentException, IOException {
		open();
		int n = reader. getNumberOfPages();
	    for (int i = 1; i <= n; i++) {
	        copy.addPage(copy.getImportedPage(reader, i));
	    }
	    copy.freeReader(reader);
	    reader.close();
	    return n;
	}
	
	/**
	 * Gets the PdfCopy instance so that you can add bookmarks or change preferences before you close PdfConcatenate.
	 */
	public PdfCopy getWriter() {
		return copy;
	}
	
	/**
	 * Opens the document (if it isn't open already).
	 * Opening the document is done implicitly.
	 */
	public void open() {
		if (!document.isOpen()) {
			document.open();
		}
	}
	
	/**
	 * We've finished writing the concatenated document.
	 */
	public void close() {
		document.close();
	}
}

⏎ com/itextpdf/text/pdf/PdfConcatenate.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