----- Mail original -----
> De: "Paul Sandoz" <paul.san...@oracle.com>
> À: "Remi Forax" <fo...@univ-mlv.fr>
> Cc: "Alan Bateman" <alan.bate...@oracle.com>, "nio-dev"
> <nio-...@openjdk.java.net>, "core-libs-dev"
> <core-libs-dev@openjdk.java.net>
> Envoyé: Mardi 1 Mai 2018 00:37:57
> Objet: Hashing files/bytes <was> Re: RFR(JDK11/NIO) 8202285: (fs) Add a
> method to Files for comparing file contents
> Thanks, better then i expected with the transferTo method we recently added,
> but
> i think we could do even better for the ease of use case of “give me the hash
> of this file contents or these bytes or this byte buffer".
yes, it can be a nice addition to java.nio.file.Files and in that case the
method that compare content can have reference in its documentation to this new
method.
>
> Paul.
Rémi
>
>> On Apr 30, 2018, at 3:23 PM, Remi Forax <fo...@univ-mlv.fr> wrote:
>>
>>>
>>> To Remi’s point this might dissuade/guide developers from using this method
>>> when
>>> there are other more efficient techniques available when operating at larger
>>> scales. However, it is unfortunately harder that it should be in Java to
>>> hash
>>> the contents of a file, a byte[] or ByteBuffer, according to some chosen
>>> algorithm (or a good default).
>>
>> it's 6 lines of code
>>
>> var digest = MessageDigest.getInstance("SHA1");
>> try(var input = Files.newInputStream(Path.of("myfile.txt"));
>> var output = new DigestOutputStream(OutputStream.nullOutputStream(),
>> digest)) {
>> input.transferTo(output);
>> }
>> var hash = digest.digest();
>>
>> or 3 lines if you don't mind to load the whole file in memory
>>
>> var digest = MessageDigest.getInstance("SHA1");
>> digest.update(Files.readAllBytes(Path.of("myfile.txt")));
>> var hash = digest.digest();
>>
>>>
>>> Paul.
>>
> > Rémi
