----- Original Message -----
> From: Donald Jolley <[email protected]>
> To: Tomcat Users List <[email protected]>
> Cc:
> Sent: Monday, August 29, 2011 5:38 PM
> Subject: Re: Exception Handling
>
>> Like... what other information do you want to
>> provide? An explanation of what to do to avoid the error? That is
>> worthy of a Turing Award if you can pull it off :)
>
> I am interested in identifying as clearly as possible the specific code that
> was the root cause of the error. The "original URI" that you
> mentioned
> sounded helpful. So far I have not been able to figure out how to do that.
> I was able to add a stack trace.
>
> So far, I am quite willing to live with what I have. Thanks for your input.
>
> ... doug
>
There's an implicit object called pageContext.
The javadoc for that (javax.servlet.jsp.PageContext) has a lot of interesting
information.
One of the methods is getErrorData. Looking at the javadoc for ErrorData
(javax.servlet.jsp.ErrorData), there's a method called getRequestURI. This
sounds exactly like what you're looking for:
${pageContext.errorData.requestURI} will give you the URI.
Also in the javadoc for pageContext, there's a method called getException,
which returns an Exception object.
java.lang.Exception implements java.lang.Throwable, which has a lot of nice
information.
One nice one is getMessage, which may give a more detailed message than the
default toString. You could access that by:
${pageContext.exception.message}
Another one is getStackTrace, which returns an array of StackTraceElement. So
you could
print the stack trace using the following code (if you've included the standard
tag lib):
<c:forEach var="st" items="${pageContext.exception.stackTrace}">
${st}<br>
</c:forEach>
This makes use of the StackTraceElement.toString() method. There are obviously
more games you can play. For example, if you don't want the entire stack trace,
you can do this:
${pageContext.exception.stackTrace[0].fileName}<br>
${pageContext.exception.stackTrace[0].lineNumber}<br>
${pageContext.exception.stackTrace[0].className}<br>
There may be more than one class you're responsible for, so the first entry in
the array might not be the most interesting one. Here's a slightly different
foreach loop which just dumps class names and line numbers:
<c:forEach var="st" items="{pageContext.exception.stackTrace}">
${st.className} ${st.lineNumber}<br>
</c:forEach>
See the java.lang.StackTraceElement for other useful features.
In short, look at implicit objects, then see what's populated when
isErrorPage="true" is set, and finally look at the javadoc for the classes.
. . . . just my two cents.
/mde/
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