You cannot do this in a JSP for exactly the reasons Paul mentioned. JSPs are solely inteneded to render character response data. Anything else, be it PDF, images  or any other binary stream, must be emitted with a servlet.

create servlet file.
for example
setContentType(application/excel); but I think it depends on your browser.

also for pdf  file setContentType(application/pdf);

open your pdf or excel file  and read its content.