com.itextpdf.io.source.MappedChannelRandomAccessSource Maven / Gradle / Ivy
/*
This file is part of the iText (R) project.
Copyright (c) 1998-2022 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: [email protected]
*/
package com.itextpdf.io.source;
import java.nio.channels.FileChannel;
/**
* A RandomAccessSource that represents a memory mapped section of an underlying FileChannel.
* This source can be closed and will automatically re-open as needed.
* This class is an internal implementation detail of the {@link FileChannelRandomAccessSource} class and
* shouldn't be used by general iText users.
*/
class MappedChannelRandomAccessSource implements IRandomAccessSource {
/**
* The underlying channel
*/
private final FileChannel channel;
/**
* The offset into the channel that this source maps to
*/
private final long offset;
/**
* The number of bytes this source maps to
*/
private final long length;
/**
* If the map is active, the actual map. null other wise.
*/
private ByteBufferRandomAccessSource source;
/**
* Create a new source based on the channel. Mapping will not occur until data is actually read.
* @param channel the underlying channel
* @param offset the offset of the map
* @param length the length of the map
*/
public MappedChannelRandomAccessSource(FileChannel channel, long offset, long length) {
if (offset < 0)
throw new IllegalArgumentException(offset + " is negative");
if (length <= 0)
throw new IllegalArgumentException(length + " is zero or negative");
this.channel = channel;
this.offset = offset;
this.length = length;
this.source = null;
}
/**
* Map the region of the channel
* @throws java.io.IOException if there is a problem with creating the map
*/
void open() throws java.io.IOException {
if (source != null)
return;
if (!channel.isOpen())
throw new IllegalStateException("Channel is closed");
source = new ByteBufferRandomAccessSource(channel.map(FileChannel.MapMode.READ_ONLY, offset, length));
}
/**
* {@inheritDoc}
*/
public int get(long position) throws java.io.IOException {
if (source == null)
throw new java.io.IOException("RandomAccessSource not opened");
return source.get(position);
}
/**
* {@inheritDoc}
*/
public int get(long position, byte[] bytes, int off, int len) throws java.io.IOException {
if (source == null)
throw new java.io.IOException("RandomAccessSource not opened");
return source.get(position, bytes, off, len);
}
/**
* {@inheritDoc}
*/
public long length() {
return length;
}
/**
* {@inheritDoc}
*/
public void close() throws java.io.IOException {
if (source == null)
return;
source.close();
source = null;
}
@Override
public String toString() {
return getClass().getName() + " (" + offset + ", " + length + ")";
}
}