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From "Honton, Charles" <Charles_Hon...@intuit.com>
Subject Re: another new URL() question
Date Mon, 11 Jun 2012 16:10:52 GMT
Mark,

The only mechanism available to extend URLClassLoader's protocol handling
in a Sun jvm is to add a URLStreamHandler.  It's a difficult task to
re-implement the class loading architecture, and I'm sure the application
server environments don't mess with this basic.  (I'm not so sure about
the Android vm)

The URLStreamHandler is used by the URL class to parse the string
representation into a URL object.  So I'm really surprised by the
situation where !url.equals(new URL(url.toExternalForm())).

You mentioned that wsjar:// failed this test.  Does websphere return this
URL from a ClassLoader.getResource()?  If so, what is the class type of
that instance? (Probably something written by websphere)

We could add a URLStreamHandler to handle parsing (and handling stream
requests for) the wsjar URL.

Chas


On 6/11/12 7:23 AM, "Matt Benson" <gudnabrsam@gmail.com> wrote:

>Hi, Mark!  This is why I was confused when we touched on this on
>IRC--I was thinking that the correct handling of URLs was an
>orthogonal function to [classscan]'s *use* of those same URLs, for
>this reason.  I had thought there had been, at one time, an OSS Java
>project to help manage these URLStreamHandlers, but I haven't had any
>luck finding it again.  If we never do, this could be a second sandbox
>component, a new piece for Commons [io], or...?  It could be an
>interesting setup to have a core management infrastructure, with any
>number of pluggable modules for different OS/container/et al
>platforms?
>
>Matt
>
>On Mon, Jun 11, 2012 at 1:56 AM, Mark Struberg <struberg@yahoo.de> wrote:
>> Regarding the new URL() problem some of you might have more experience
>>than I do. I only know the problems on some platforms, and after looking
>>at the URL class in detail, I really wonder whether that was me doing it
>>wrong or a platform bug.
>>
>> My understanding problem is mainly around the URLStreamHandler. There
>>is a method where one can set a URLStreamHandlerFactory (once for JVM
>>lifetime):
>>
>> URL#setURLStreamHandlerFactory(URLStreamHandlerFactory fac)
>>
>> Thus when a ClassLoader#getResources() returns an URL with "wsjar://"
>>as protocol and it cannot be used for new URL(), then can I safely
>>assume this is a problem in the container setup? This happens on Oracles
>>own WebLogic...
>>
>> I have not yet tried the following way:
>>
>> String protocol = "wsjar";
>> URLStreamHandler getURLStreamHandler(protocol)
>>
>> and then use the following URL constructor:
>>
>> public URL(URL context, String spec, URLStreamHandler handler)
>>
>>
>> Can anyone test if this works? Or does anyone know already?
>> We might hack a small JSP page which scans for META-INF/MANIFEST.MF and
>>reports errors with new URL(). That way we could spread the test onto
>>various platforms.
>>
>> LieGrue,
>> strub
>>
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