Getting a File Output Stream into a Blob column

I have dynamically created a PDF document in memory as a FileOutputStream. Now I have to get it into a DB2 table, storing it as a BLOB. The table has a document id,
document name, some date fields and this BLOB column that stores PDF Files. Until now, the PDF files were read off of a disk drive. The code used was:

byte[] fileAsBytes = (byte[]) adminDocEvent.getFile();

which returns an object.
then:
"INSERT INTO WPWDB.DOC_DOCUMENT ("
+ "DOC_SUB_CAT_ID,"
+ "DOC_DOC_NM_TXT,"
+ "DOC_DOC_DESCN_TXT,"
+ "DOC_ACTIVE_TXT,"
+ "DOC_DOC_LNK_TXT,"
+ "DOC_DOC_MIME_TYP,"
+ "MODIFY_USUS_ID,"
+ "MODIFY_DT_TM)"
+ " VALUES (?,?,?,?,?,?,?,CURRENT TIMESTAMP)";

connection = getConnection();

pstmt = connection.prepareStatement(query);
pstmt.setInt(1, subCatId);
pstmt.setString(2, docName);
pstmt.setString(3, docDescription);
pstmt.setString(4, "Y");
==> pstmt.setBytes(5, fileasarray);
pstmt.setString(6, mimeType);
pstmt.setString(7, modfiedUserID);
pstmt.executeUpdate();

This is fine, if the pdf file exists as a file on a disk.
For my issue (loading a pdf file from memory) I use the following:

private FileOutputStream fos = new FileOutputStream(docName);
private PdfWriter docWriter = null;
docWriter=PdfWriter.getInstance(pdfDocument, fos);
I then create the pdfDocument in memory using iText classes.
Then I try to prepare the file for the above sql stmt.

file = (Object) fos;
AdminDocDAO adminDocDAO = new AdminDocDAO();
if (adminDocDAO.addDoc(subCatId,docName,docDescription,fileAsBytes, mimeType,modifiedUserID))

I get a casting exeception at: file = (Object) fos;

So my question is can anyone think of another approach to getting a FileOutputStream in memory, into a format loadable in SQL using DB2???????
Thanks to any and all who can.