org.h2.store.fs.FileChannelInputStream Maven / Gradle / Ivy
/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.store.fs;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
/**
* Allows to read from a file channel like an input stream.
*/
public class FileChannelInputStream extends InputStream {
private final FileChannel channel;
private final boolean closeChannel;
private ByteBuffer buffer;
private long pos;
/**
* Create a new file object input stream from the file channel.
*
* @param channel the file channel
* @param closeChannel whether closing the stream should close the channel
*/
public FileChannelInputStream(FileChannel channel, boolean closeChannel) {
this.channel = channel;
this.closeChannel = closeChannel;
}
@Override
public int read() throws IOException {
if (buffer == null) {
buffer = ByteBuffer.allocate(1);
}
buffer.rewind();
int len = channel.read(buffer, pos++);
if (len < 0) {
return -1;
}
return buffer.get(0) & 0xff;
}
@Override
public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
ByteBuffer buff = ByteBuffer.wrap(b, off, len);
int read = channel.read(buff, pos);
if (read == -1) {
return -1;
}
pos += read;
return read;
}
@Override
public void close() throws IOException {
if (closeChannel) {
channel.close();
}
}
}