Hey all,
I just spent about 20 minutes working through a problem with FileUpload...
turned out to be my fault entirely, I didn't include Commons IO (FYI, I'm
not seeing a dependency list on the FileUpload site... maybe I missed it).
The problem is, it was one of those aggrevating problems to track down
because the stack trace didn't reveal the actual line where the failure
occured, and catching Exception didn't get triggered. I wound up catching
Throwable, and I was then able to figure it out.
I know that missing dependencies is always a b**ch, and they tend to be
these annoying problems with no error messages or anything (sure, a
debugger helps, but that doesn't seem like the best answer to me). So, I
have a suggestion that could well go all across Commons, or any other
project for that matter.
In Java Web Parts, we've gotten into the habit of putting this in all
classes:
/**
* This static initializer block tries to load all the classes this one
* depends on (those not from standard Java anyway) and prints an error
* meesage if any cannot be loaded for any reason.
*/
static {
try {
Class.forName("org.apache.commons.logging.Log");
Class.forName("org.apache.commons.logging.LogFactory");
} catch (ClassNotFoundException e) {
System.err.println("CacheControlFilter" +
" could not be loaded by classloader because classes it depends" +
" on could not be found in the classpath...");
e.printStackTrace();
}
}
It's just echoing the import list, minus classes found in the SDK (if
that's missing, you aren't getting *this* far!). This saves a lot of time
and headache when you are missing a dependency. I know that adds
something additional to maintain in the class, but it seems a fair
trade-off to me.
Does anyone see this as being something that might be helpful for Commons?
If there is a better way to get the same effect I'm all ears too (I could
see setting a string to the name of the class being checked so that it
could be output as part of the error message, but I'm talking about a
whole other way to check for dependencies).
--
Frank W. Zammetti
Founder and Chief Software Architect
Omnytex Technologies
http://www.omnytex.com
AIM: fzammetti
Yahoo: fzammetti
MSN: [EMAIL PROTECTED]
Java Web Parts -
http://javawebparts.sourceforge.net
Supplying the wheel, so you don't have to reinvent it!
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