u have to do the following things :
>first of all select the row from oracle  db.
>then get the BLOB from resultset(use orcle BLOB interface plz don't use
java.sql.Blob
> now open a input stream from BLOB (u can find it in BLOB interface)
>now read from the input stream and write it to a local file  system or u can use
this input stream for zipinputstream.

thats it.