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