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From MANDAR RAJE <man...@pathfinder.eng.sun.com>
Subject Re: Jasper Name Mangling Question - repost
Date Mon, 12 Jun 2000 20:40:00 GMT
Steve Appling wrote:
> 
> Jasper's JSP name mangling is causing me some problems, but I don't know if it
> is operating in this fashion by design or because of a bug.  I'm using the 3.1
> release.
> 
> When compiling a JSP, jasper creates a directory structure under my scratchdir
> that mimics the path to my jsp (as expected).  It then creates the java source
> file (and resulting class) in the root of the scratchdir in a mangled form
> (including substituting the "/" in the path with "_0002f").  Between mangling
> the "/" and "_" characters, the resulting file names are often too long to
> create
> under Win98 (>256 chars).

 I have seen this particular problem mentioned before. What we need
(maybe) is a simple fix -- one that (for example) ignores '/' and
'-' characters. This will not gurantee a unique class name, but
probability of having name collisions will still be very low, also
making the file name relatively smaller. 


> 
> Why does jasper create a directory structure under the scratchdir and not use
> it?  It would seem to be better to put an unmangled file name in the appropriate
> directory.

 The main reason is that Jasper needs to compare the time-stamps
and constructing a proper path name to the class file to find out
"last-modified time" at runtime is somewhat expensive. Ofcourse
things can be cached -- maybe one of the to-do things.

> 
> It is also not clear to me why the generated classes have the appended version
> numbers.  Is it necessary to keep multiple versions of the same jsp loaded
> simultaneously for some reason?  If the generated java file name / class file
> name / class name were the same, then the ClassFileData.findClassName call
> wouldn't be so expensive - it wouldn't have to parse the class file data to
> determine the class name.
> 
> This all seems overly complicated - I must be missing something.  I would
> appreciate any clarifications.

 This is to support JSP reloading. If you modify a JSP, you use
a different version number and generate a different 
class which can then be loaded (A class with the same name can't
be loaded if its been loaded before).

Thanks,
Mandar.

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