On Mon, May 18, 2020 at 08:00:16PM -0000, John Calcote wrote:
> I'm trying to create a sort of multi-part download mechanism using jclouds
> download with a GetOption of "range". I'd like to just download 5MB ranges
> until I run out of file to download. The doc on the use of this option is a
> bit sparse. Can someone help me understand the semantics of download with a
> range option?
>
> Here's what I'd like to do:
>
> long start = 0;
> long size = 5 * 1024 * 1024;
> long length = size;
>
> while (length < size) {
> long limit = start + size
> Blob blob = getBlob(container, key, range(start, limit - 1));
> ContentMetadata meta = blob.getMetadata().getContentMetadata();
> long length = meta.getContentLength();
>
> // stream 'length' bytes into a buffer and process the buffer here
>
> start = limit;
> }
>
> Assumptions:
> 1) content length will return the actual size downloaded if it's less than
> the range size specified.
> 2) It's OK to request a range of bytes that's outside the file extant -
> you'll just get back a length of zero.
BlobStore.getBlob takes an optional argument that you can populate via:
new GetOptions().range(start, size)
Note that this range is inclusive.
--
Andrew Gaul
http://gaul.org/
