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/* ====================================================================
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==================================================================== */
package org.apache.poi.poifs.nio;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;
import org.apache.poi.util.IOUtils;
/**
* A POIFS {@link DataSource} backed by a File
*/
public class FileBackedDataSource extends DataSource {
private FileChannel channel;
private boolean writable;
@SuppressWarnings("resource")
public FileBackedDataSource(File file) throws FileNotFoundException {
if(!file.exists()) {
throw new FileNotFoundException(file.toString());
}
this.channel = (new RandomAccessFile(file, "r")).getChannel();
this.writable = false;
}
public FileBackedDataSource(FileChannel channel, boolean readOnly) {
this.channel = channel;
this.writable = !readOnly;
}
public boolean isWriteable() {
return this.writable;
}
@Override
public ByteBuffer read(int length, long position) throws IOException {
if(position >= size()) {
throw new IllegalArgumentException("Position " + position + " past the end of the file");
}
// Do we read or map (for read/write?
ByteBuffer dst;
int worked = -1;
if (writable) {
dst = channel.map(FileChannel.MapMode.READ_WRITE, position, length);
worked = 0;
} else {
// Read
channel.position(position);
dst = ByteBuffer.allocate(length);
worked = IOUtils.readFully(channel, dst);
}
// Check
if(worked == -1) {
throw new IllegalArgumentException("Position " + position + " past the end of the file");
}
// Ready it for reading
dst.position(0);
// All done
return dst;
}
@Override
public void write(ByteBuffer src, long position) throws IOException {
channel.write(src, position);
}
@Override
public void copyTo(OutputStream stream) throws IOException {
// Wrap the OutputSteam as a channel
WritableByteChannel out = Channels.newChannel(stream);
// Now do the transfer
channel.transferTo(0, channel.size(), out);
}
@Override
public long size() throws IOException {
return channel.size();
}
@Override
public void close() throws IOException {
channel.close();
}
}
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