Wrapping a business exception in ServletException in doPost()

[Bindu Lakhanpal]

This is from Enthuware:

Which of the following is a sensible way of sending an error page to the client in case of a business exception that extends from java.lang.Exception?


C. Catch the exception, wrap it into ServletException and define the 'business exception to error-page' mapping in web.xml----Answer

D.Catch the exception, wrap it into ServletException, and define the 'ServletException to error-page' mapping in web.xml

Why D is not an answer?
We have wrapped our business exception in ServletException and throwing ServletException so web.xml should have ServletException to error-page mapping.
Why C is correct? Since we are throwing ServletException why the mapping in web.xml should be businessException to error-page


They have explanation giving following code:

//in doPost() of AccountServlet

try 
{ 
	...lot of code
	if(funds<amt) throw new NotEnoughFundsException(); 
	...lot of code

} 
catch(NotEnoughFundsException nfe) 
{ 
	throw new ServletException(nfe) // wrap the exception inside ServletException 
} 

The error mapping in DD should be:

><exception-type>com.mycorp.NotEnoughFundsException</exception-type> 
<location>/errorPage.jsp</location>

[Tripati Sahu]

Suppose I want to configure 4-5 different kind of exceptions then how you will configure...

If we will configure servlet exception then it will always go fo it.

Guys please correct me If I am wrong.

[Bindu Lakhanpal]

Yes. And i read the "sensible way " in question .
But we are throwing a servletException and catching a business exception.
Or is it not the way it appears and it is actually business exception being thrown?
Howcome?

[Bindu Lakhanpal]

I got the answer in SRV.9.9.2 !

If no error-page declaration containing an exception-type fits using the
class-heirarchy match, and the exception thrown is a ServletException or
subclass thereof, the container extracts the wrapped exception, as defined by the
ServletException.getRootCause method. A second pass is made over the error
page declarations, again attempting the match against the error page declarations,
but using the wrapped exception instead.