import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class Main {
public static void main(String[] args) throws Exception {
String source = "s.txt";
String destination = "d.txt";
FileInputStream fis = new FileInputStream(source);
FileOutputStream fos = new FileOutputStream(destination);
FileChannel fci = fis.getChannel();
FileChannel fco = fos.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(1024);
while (true) {
int read = fci.read(buffer);
if (read == -1)
break;
buffer.flip();
fco.write(buffer);
buffer.clear();
}
}
}