The apache (HYPERLINK "http://www.apache.org/"www.apache.org) project
has something which allows you to read  H.S.F. aka Excel files (Horrible
Spreadsheet Format) maybe that will point you in the right direction.
I¡Çm not sure for PDF

For reading PDF files you can try iText available at
http://www.lowagie.com/iText/

I think you got use the binary read  format and as well
as the java.swing.text package to do this.

I have learned to try to create Word document viewer using some manual tools these days:
www.rasteredge.com/.../