Integrated: 8329829: HttpClient: Add a BodyPublishers.ofFileChannel method

[Volkan Yazici]

On Mon, 7 Jul 2025 07:33:58 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

> Adds a new `ofFileChannel(FileChannel channel, long offset, long length)` method to `java.net.HttpRequest.BodyPublishers` to provide an `HttpClient` publisher to upload a certain region of a file. The new publisher does not modify the state of the passed `FileChannel`, streams the file channel bytes as it publishes (i.e., avoids reading the entire file into the memory), and can be leveraged to implement sliced uploads. As noted in the Javadoc:
> 
>> The file channel will not be closed upon completion. The caller is
>> expected to manage the life cycle of the channel, and close it
>> appropriately when not needed anymore.
> 
> ### Implementation notes
> 
> - `FileChannel` is preferred over `{Readable,Seekable}ByteChannel`, since the latter does not provide a positional read without modifying the state of the `FileChannel`, which is necessary to use a single `FileChannel` instance to implement sliced uploads.
> - `ofFileChannel(FileChannel,long,long)` is preferred over `ofPath(Path,long,long)` to avoid overloading the maximum file descriptor limit of the platform.

This pull request has now been integrated.

Changeset: dacd9af9
Author:    Volkan Yazici <vyazici at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/dacd9af9a02464d2d6144e29d851216641e836c9
Stats:     851 lines in 4 files changed: 846 ins; 2 del; 3 mod

8329829: HttpClient: Add a BodyPublishers.ofFileChannel method

Reviewed-by: dfuchs, jpai, michaelm

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PR: https://git.openjdk.org/jdk/pull/26155