The user uploaded files can be displayed in a web page using servlet/jsp by reading the physical file (FileReader etc). Then the bytes of the read stream can be written into the output stream of servlet to display the read files in web page.
BufferedReader in = new BufferedReader(new FileReader("absoulte path name"));
No pain, No gain.
OCJP 1.6, Liferay Certified Developer 6.1