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/MappedRandomAccessFile.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.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.Method;
import java.nio.BufferUnderflowException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.AccessController;
import java.security.PrivilegedAction;

/**
 * A {@link java.nio.MappedByteBuffer} wrapped as a {@link java.io.RandomAccessFile}
 *
 * @author Joakim Sandstroem
 * Created on 6.9.2006
 */
public class MappedRandomAccessFile {

    private static final int BUFSIZE = 1 << 30;
    
    private FileChannel channel = null;
    private MappedByteBuffer[] mappedBuffers;
    private long size;
    private long pos;

    /**
     * Constructs a new MappedRandomAccessFile instance
     * @param filename String
     * @param mode String r, w or rw
     * @throws FileNotFoundException
     * @throws IOException
     */
    public MappedRandomAccessFile(String filename, String mode)
    throws FileNotFoundException, IOException {

        if (mode.equals("rw"))
            init(
                    new java.io.RandomAccessFile(filename, mode).getChannel(),
                    FileChannel.MapMode.READ_WRITE);
        else
            init(
                    new FileInputStream(filename).getChannel(),
                    FileChannel.MapMode.READ_ONLY);

    }

    /**
     * initializes the channel and mapped bytebuffer
     * @param channel FileChannel
     * @param mapMode FileChannel.MapMode
     * @throws IOException
     */
    private void init(FileChannel channel, FileChannel.MapMode mapMode)
    throws IOException {

        this.channel = channel;
        
        
        size = channel.size();
        pos = 0;
        int requiredBuffers = (int)(size/BUFSIZE) + (size % BUFSIZE == 0 ? 0 : 1);
        //System.out.println("This will require " + requiredBuffers + " buffers");
        
        mappedBuffers = new MappedByteBuffer[requiredBuffers];
        try{
            int index = 0;
            for(long offset = 0; offset < size; offset += BUFSIZE){
                long size2 = Math.min(size - offset, BUFSIZE);
                mappedBuffers[index] = channel.map(mapMode, offset, size2);
                mappedBuffers[index].load();
                index++;
            }
            if (index != requiredBuffers){
                throw new Error("Should never happen - " + index + " != " + requiredBuffers);
            }
        } catch (IOException e){
            close();
            throw e;
        } catch (RuntimeException e){
            close();
            throw e;
        }
        
    }

    /**
     * @since 2.0.8
     */
    public FileChannel getChannel() {
    	return channel;
    }

    /**
     * @see java.io.RandomAccessFile#read()
     * @return int next integer or -1 on EOF
     */
    public int read() {
        try {
            int mapN = (int) (pos / BUFSIZE);
            int offN = (int) (pos % BUFSIZE);
            
            if (mapN >= mappedBuffers.length) // we have run out of data to read from
                return -1;
            
            if (offN >= mappedBuffers[mapN].limit())
                return -1;
            
            byte b = mappedBuffers[mapN].get(offN);
            pos++;
            int n = b & 0xff;

            return n;
        } catch (BufferUnderflowException e) {
            return -1; // EOF
        }
    }

    /**
     * @see java.io.RandomAccessFile#read(byte[], int, int)
     * @param bytes byte[]
     * @param off int offset
     * @param len int length
     * @return int bytes read or -1 on EOF
     */
    public int read(byte bytes[], int off, int len) {
        int mapN = (int) (pos / BUFSIZE);
        int offN = (int) (pos % BUFSIZE);
        int totalRead = 0;
        
        while(totalRead < len){
            if (mapN >= mappedBuffers.length) // we have run out of data to read from
                break;
            MappedByteBuffer currentBuffer = mappedBuffers[mapN];
            if (offN > currentBuffer.limit())
                break;
            currentBuffer.position(offN);
            int bytesFromThisBuffer = Math.min(len - totalRead, currentBuffer.remaining());
            currentBuffer.get(bytes, off, bytesFromThisBuffer);
            off += bytesFromThisBuffer;
            pos += bytesFromThisBuffer;
            totalRead += bytesFromThisBuffer;

            mapN++;
            offN = 0;
            
        }
        return totalRead == 0 ? -1 : totalRead;
    }

    /**
     * @see java.io.RandomAccessFile#getFilePointer()
     * @return long
     */
    public long getFilePointer() {
        return pos;
    }

    /**
     * @see java.io.RandomAccessFile#seek(long)
     * @param pos long position
     */
    public void seek(long pos) {
        this.pos = pos;
    }

    /**
     * @see java.io.RandomAccessFile#length()
     * @return long length
     */
    public long length() {
        return size;
    }

    /**
     * @see java.io.RandomAccessFile#close()
     * Cleans the mapped bytebuffer and closes the channel
     */
    public void close() throws IOException {
        for(int i = 0; i < mappedBuffers.length; i++){
            if (mappedBuffers[i] != null){
                clean(mappedBuffers[i]);
                mappedBuffers[i] = null;
            }
        }

        if (channel != null)
            channel.close();
        channel = null;
    }

    /**
     * invokes the close method
     * @see java.lang.Object#finalize()
     */
    @Override
    protected void finalize() throws Throwable {
        close();
        super.finalize();
    }

    /**
     * invokes the clean method on the ByteBuffer's cleaner
     * @param buffer ByteBuffer
     * @return boolean true on success
     */
    public static boolean clean(final java.nio.ByteBuffer buffer) {
        if (buffer == null || !buffer.isDirect())
            return false;

        Boolean b = (Boolean) AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
            public Boolean run() {
                Boolean success = Boolean.FALSE;
                try {
                    Method getCleanerMethod = buffer.getClass().getMethod("cleaner", (Class<?>[])null);
                    getCleanerMethod.setAccessible(true);
                    Object cleaner = getCleanerMethod.invoke(buffer, (Object[])null);
                    Method clean = cleaner.getClass().getMethod("clean", (Class<?>[])null);
                    clean.invoke(cleaner, (Object[])null);
                    success = Boolean.TRUE;
                } catch (Exception e) {
                    // This really is a show stopper on windows
                    //e.printStackTrace();
                }
                return success;
            }
        });

        return b.booleanValue();
    }

}

⏎ com/itextpdf/text/pdf/MappedRandomAccessFile.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