Handle exception.
Parameters: request - the request we are processing Parameters: response - the response we are creating Parameters: actionConfig - the action configuration Parameters: exception - the exception that occured during action invocation a DispatchConfig instance describing where and howcontrol should be forwarded/included, or null if theresponse has already been completed. exception: IOException - may be thrown if the exception could not be handled. exception: ServletException - may be thrown if the exception could not be handled.