Issue: Modules can only open resources as streams

David M. Lloyd david.lloyd at
Mon Mar 21 14:14:15 UTC 2016

On 03/03/2016 09:42 AM, David M. Lloyd wrote:
> Module.getResourceAsStream() is the only way a resource can be loaded
> from a module.  This makes it impossible to do either of the following:
> • Determine the size of a resource in advance of loading it
> • Determine the existence of a resource without opening it
> Loading resources as allowed these things to be done
> (among other things), however it is also disadvantageous due to the
> heavyweight nature of that class.
> I had earlier come up with a simple patch [1], initially as a way to
> address JDK-6865375 [2], which introduced the idea of a Resource class
> that is associated with a ClassLoader, with a name, URL, size, and
> stream factory method, which would also be a clean solution here (though
> with the addition of a Module property as well since in Jigsaw they're
> separate).
> The idea is to put resources on a similar footing to classes, whereby
> you can (if suitably permitted) acquire their class loaders just like
> Class.getClassLoader() allows you to do for classes.  This also allows
> things like ServiceLoader to load classes directly from the module which
> contained the corresponding service descriptor.
> [1]
> [2]

Without any further discussion I'm going to assume complete agreement 
with the definition and acceptance of the problem and (at least the 
general gist of) the proposed solution.  If any of you disagree with 
this issue on any basis, PLEASE speak up ASAP otherwise I will assume 
that the group is in agreement!


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