Can't upload file to server from my jsp page

[shih_yao_yang]

Hi,
I have a problem that I uploaded a .war file to plesk.
But I can't upload file from my jsp page.
I got a null from when I call "getServletContext().getRealPath(".")"
It seems that I can't get the full path of my homepage.
Does anyone know how to resolve this problem?
Thanks,

Yao