| /* ==================================================================== |
| 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; |
| |
| public FileBackedDataSource(File file) throws FileNotFoundException { |
| if(!file.exists()) { |
| throw new FileNotFoundException(file.toString()); |
| } |
| this.channel = (new RandomAccessFile(file, "r")).getChannel(); |
| } |
| public FileBackedDataSource(FileChannel channel) { |
| this.channel = channel; |
| } |
| |
| public ByteBuffer read(int length, long position) throws IOException { |
| if(position >= size()) { |
| throw new IllegalArgumentException("Position " + position + " past the end of the file"); |
| } |
| |
| // Read |
| channel.position(position); |
| ByteBuffer dst = ByteBuffer.allocate(length); |
| int 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; |
| } |
| |
| public void write(ByteBuffer src, long position) throws IOException { |
| channel.write(src, position); |
| } |
| |
| 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); |
| } |
| |
| public long size() throws IOException { |
| return channel.size(); |
| } |
| |
| public void close() throws IOException { |
| channel.close(); |
| } |
| } |