RFR: Let jar tool print timestamps in default locale date and time in format

[Xueming Shen]

It's an "incompatible" change, presumably lots of existing scripts which 
may depend on the output format
of existing implementation, will be broken by this one.

Yes, the default timestamp in zip entry is dos datetime...Though the 
support for "more accurate" timestamp
for zip file has been added (ZIS, ZOS and ZipFile), but due to its size 
increase of the resulting zip file, jar tool
does not use it, yet.

-Sherman

On 3/6/15 6:49 AM, Jacob Wisor wrote:
> Hello there!
>
> I have stumbled upon the jar tool always printing nominally the same 
> date and time for a JarEntry, regardless of the timezone set. Confused 
> by this, I dug into the code only to find out that the zip file format 
> does neither store timezone information nor timestamps in UTC. This 
> basically means that timestamps in jar/zip files are or can be assumed 
> to always be in the local timezone, hence there is no conceivable fix 
> for this problem, except for altering the zip file format 
> specification. However, timestamps are printed in the en_US locale 
> currently. This locale is /almost/ as arbitrary as every other. So, 
> this patch makes the jar tool print timestamps in the default locale 
> date and time format.
>
> If anybody is bothered by this change they can still explicitly set 
> the user.language property or the system's locale to en_US.
> If anybody /really/ wants to parse jar tool's timestamps output they 
> should probably be relying on ISO formatted timestamps. I can add this 
> functionality as a flag.
>
> Anyways, please review this patch.
>
> Regards,
>
> Jacob