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/io/RandomAccessSource.java

/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
 * Authors: Kevin Day, Bruno Lowagie, 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 License for more
 * details. You should have received a copy of the GNU Affero General 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 License.
 *
 * In accordance with Section 7(b) of the GNU Affero General 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.io;

import java.io.IOException;

/**
 * Represents an abstract source that bytes can be read from.  This class forms the foundation for all byte input in iText. 
 * Implementations do not keep track of a current 'position', but rather provide absolute get methods.  Tracking position
 * should be handled in classes that use RandomAccessSource internally (via composition).
 * @since 5.3.5
 */
public interface RandomAccessSource {
	/**
	 * Gets a byte at the specified position
	 * @param position
	 * @return the byte, or -1 if EOF is reached
	 */
	public int get(long position) throws IOException;
	
	/**
	 * Gets an array at the specified position.  If the number of bytes requested cannot be read, the bytes that can be
	 * read will be placed in bytes and the number actually read will be returned.
	 * @param position the position in the RandomAccessSource to read from
	 * @param bytes output buffer
	 * @param off offset into the output buffer where results will be placed
	 * @param len the number of bytes to read
	 * @return the number of bytes actually read, or -1 if the file is at EOF
	 */
	public int get(long position, byte bytes[], int off, int len) throws IOException;
	
	/**
	 * @return the length of this source
	 */
	public long length();
	
	/**
	 * Closes this source.  The underlying data structure or source (if any) will also be closed
	 * @throws IOException
	 */
	public void close() throws IOException;
	
}

⏎ com/itextpdf/text/io/RandomAccessSource.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