This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
By default till struts version 1.1 there, struts did not have much of exception handling, developers had to work on the code to do effective exception handling. But later versions of struts have good exception handling techniques. Depending upon whether it is runtime or compile time exception struts can handle thing. For example in your code, say user when not able to log-on successfully, then it has to be redirected to a graceful error page with an exception. In this case you can use the "<exception>" in "struts.config". Another one that will help a lot is ModuleException api, I think it extends exception and action errror class,Classic api that can be used for various scenarios. As well ExceptionHandler is another handy. If you want to display error messages in your JSP, I would take a look at ActionErrors and ActionMessages Api. Hope it helps.
#common module error message
error.exception.message = This Exception Message Generated By Struts 1.3 Exception Handler Example
label.name = User Name
label.submit = Submit
label.reset = Reset
error.name.required = User Name Resquired
label.title = Struts 1.3 Exception Handler Example
label.header = Struts 1.3 Exception handler Example