How to download a pdf file stored in a MySQL blob?

I want to know what should I put inside a jbutton action listener.

I think I knew how to get the row in the table where the blob file exists

and place the Blob file into a variable

Blob pdffile = rs.getBlob(6)

the problem is i don't know what to do with the pdffile(blob) to save it in a local directory

See the API for Blob, in particular the getBinaryStream() method, which retrieves an InputStream