[ajug-members] Chaining OutputStreams

[Ben McEwen]

I haven't used iText in a while, but I think the PdfEncryptor writes the
encrypted PDF to the output stream; you shouldn't need to do anything with
the ServletOutputStream otherthan passing it to the PdfEncryptor.encrypt
function.  I have not tested this, but I think this is all you need to do:


	ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
	PdfReader reader = new PdfReader("WEB-INF/" + filename);

	PdfEncryptor.encrypt(reader, baos, true, userPwd, null,
		PdfWriter.AllowPrinting | PdfWriter.AllowDegradedPrinting);

	/* Set response header info and content type */
	
	//Set the response's content length
	response.setContentLength(baos.size());

	// Flush byte array to servlet output stream.
	ServletOutputStream out = response.getOutputStream();
	baos.writeTo(out);
	out.flush();
            
Hope that helps,
Ben


-----Original Message-----
From: ajug-members-bounces at ajug.org [mailto:ajug-members-bounces at ajug.org]
On Behalf Of Lee Grey
Sent: Monday, April 11, 2005 6:03 AM
To: ajug-members at ajug.org
Subject: [ajug-members] Chaining OutputStreams

I'm trying to use iText (http://www.lowagie.com/iText) to encrypt a PDF
before sending it through a servlet.  I'm confused by the use of
BufferedInputStream and BufferedOutputStream, when you need something in the
middle.  I need to take output from the PDFEncryptor and then stream that
out to the servlet response, but I don't know how to do that.  This was all
working fine when I had a BufferedInputStream reading a file from disk, but
now I've got a second OutputStream, and I don't know how to feed one from
the other.  Here's what I've got, which is probably a mess.

            // transmit encrypted file
            ServletOutputStream out = response.getOutputStream();
            BufferedOutputStream buf = new BufferedOutputStream(out);
            BufferedOutputStream bos = new BufferedOutputStream(buf);
            String filename = JFig.getInstance().getValue("file1",
"filename");
            try {
                // encrypt the file
                PdfReader reader = new PdfReader("WEB-INF/" + filename);
                String userPwd = StringUtil.createPDFPassword();
                PdfEncryptor.encrypt(reader, bos, true, userPwd, null,
PdfWriter.AllowPrinting | PdfWriter.AllowDegradedPrinting);

                byte[] buffer = new byte[4*1024];
                int totalBytes = 0;
                int bytesRead;
                while(( bytesRead = bos.read(buffer, 0, buffer.length))
!= -1) {
                    out.write(buffer, 0, bytesRead);
                    totalBytes += bytesRead;
                }
                log.debug("wrote " + totalBytes + " bytes");
                out.flush();
            } catch(Exception e) {
                if( log.isErrorEnabled() ) {
                    log.error("Failure during streaming of " + filename, e);
                }
            } finally {
                if( buf != null )
                    buf.close();
                if( bos != null )
                    bos.close();
                if( out != null ) {
                    out.flush();
                    out.close();
                }
            }

The big problem comes in the while loop, where you have to have an
InputStream to be able to call read().  Maybe that's not a problem, if you
know what you're doing.  Can someone please show me how to send the output
of the PdfEncryptor out to the servlet response stream?

Thanks,
Lee Grey
Grey Matter
http://www.leegrey.com/hmm

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