new DefaultFileRegion(raf.getChannel(), 0, fileLength);
writeFuture = ch.write(region);
writeFuture.addListener(new ChannelFutureProgressListener() {
@Override
public void operationComplete(ChannelFuture future) {
region.releaseExternalResources();
}
@Override
public void operationProgressed(
ChannelFuture future, long amount, long current, long total) {