How to stop processing a JSP early?

Question

I've got a JSP page, which calls a function and checks its return value. If the return value is not null, the JSP page goes on to use it. If the return value IS null, I want the processing of the JSP page to stop (this is because the function will perform a redirect before returning the null object. Also, the rest of the JSP code obviously uses this object, and will get a null pointer exception if the function returned null).

So my question is, what is the right way of stopping the load of a JSP page? Can I do something like this:

if (Func() == null) { return; }

Or is using a return in the middle of a JSP not the cleaner way to go about this?

Thanks

Answer 1

Regardless of how to terminate processing of a JSP early, I would suggest handling flow control in a servlet prior to handling the display, and switch to an appropriate JSP depending on the outcome of the function call.

I tend to use JSPs purely for displaying the contents of a bean (or more than one), and all logic is contained within the invoking servlet. By doing this you get a much cleaner separation of concerns between your components, and a more easily comprehensible and debuggable system.

Answer 2

Since 2.0, there is a standard way:

throw new javax.servlet.jsp.SkipPageException();

Answer 3

Brian's answer is a good advice, but it does not answer the question clearly.

The answer is YES. Bulk of JSP is converted to a method _jspService, which is being run when JSP is "executed", and since it is a regular function, that does cleanup in finally block, it is safe to return.