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From Horváth, Ákos Péter (JIRA) <>
Subject [jira] [Created] (WW-3956) silent failure of filter initialization if struts.action.excludePattern contains invalid regexp
Date Thu, 03 Jan 2013 22:38:12 GMT
Horváth, Ákos Péter created WW-3956:

             Summary: silent failure of filter initialization if struts.action.excludePattern
contains invalid regexp
                 Key: WW-3956
             Project: Struts 2
          Issue Type: Bug
          Components: Dispatch Filter
    Affects Versions: 2.3.8
         Environment: all
            Reporter: Horváth, Ákos Péter

If the struts.action.excludePatterns constant contains an invalid regexp (for example, it
begins with a "*"), the dispatcher can't initialize, but only an "Error filterStart" message
will be logged, and the web app won't work. Imho, the expected behavior were a stack trace
or a more descriptive error message.

The cause of the problem: the buildExcludedPatternList() method of
builds a compiled pattern list of the comma-separated patterns given in this constant with
java.util.regex.Pattern.compile() . This emits an IllegalArgumentException or a PatternSyntaxException,
if invalid regexp is given, but this exception somewhere silently disappears on his way to
the log.


I suggest to make a minimal example in the documentation:


is what most developer wants from this constant. For me take hours to investigate this. Googling
for "struts.action.excludePattern" reveals a lot of confusion about this, too. The greatest
source of the confusion is that it isn't clear, and isn't anywhere documented, which is the
exact regexp syntax here to apply. For example: pattern matching or regular expression, "^"
and "$" are valid or not, they are needed or not, "." matches only "." or any character, etc.
I think, the original inaccuracy was committed by sun, when they named a class as "Pattern",
which operates with regexps. What you here can do, is a single-line minimal-example in the
doc, which will explain everything.

Thank you,


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