Question

I am working with the iText library to do some PDF manipulation in Java, but I am trying to do something in which the iText API is starting to overwhelm me. I really just need a quick tutorial, or some pseudo-code, but here is what I am trying to accomplish:

1. User selects a series of check boxes, indicating which PDFs he or she wishes to print.
2. Based on user input, grab 1 – x PDF template files. Each page has a series of AcroFields which need to be filled out.
3. One such page requires drawing some custom graphics on the PDF, i.e. accessing the PdfContentByte object and manipulating that to insert images and rectangles.
4. If it possible, I would like to avoid writing temporary PDFs to disk. The previous programmer did this, and it has been messy to deal with that. I’d much prefer to grab the template file, manipulate it in memory and serve it directly to the browser.

I seem to have all the pieces, but I can’t quite put it all together. Point #4 is what’s been really tripping me up.

TIA.

Answer 1

So, here is the answer I was finally able to come up with:

//Open an input stream to the PDF template
InputStream is = getInputStreamToEachFile();


//Declare a document object, as well as a PdfCopy for
//copying in each PdfFile we open in memory and edit.
Document doc = new Document();
PdfCopy copy = new PdfCopy(doc, outputStreamToBrowser);


//Be sure to open the document or it will throw an exception!
doc.open();


//Since the PdfStamper class wants to output everything to an
//output stream you can declare a ByteArrayOutputStream object
//and direct it there, since we need to tack on more PDFs and
//can't just output to the response's output stream directly.
ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
PdfStamper stamper = new PdfStamper(new PdfReader(is), byteStream);


//Pseduocode - set form fields - just check out
//the documentation for AcroFields in the API
//this part is easy.
...


//if form has custom graphics declare a PdfContentByte array
//the 1 argument in the getUnderContent refers to the page number

PdfContentByte cb = stamper.getUnderContent(1);

//pseduocode - do custom graphics. This can be a lot of different things,
//so check the documentation
...


//Wrap things up - set the dyanamic form fields to read only
//and call the stamper's close function to close the streams
stamper.setFormFlatterning(true);
stamper.close()


//Finally, declare a new PdfReader, reading the stamper's byte array stream
//which was declared in memory.
PdfReader outReader = new PdfReader(byteStream.toByteArray());

//Use this function call to add each page that you need. Repeat this process
//for as many PDFs as are being stitched together.
copy.addPage(copy.getImportedPage(outReader,1));

//Finally, tell the browser you are done generating the file, and output it.
//If there are a lot of pages being generated this way, I guess you could use the flush
//function instead, and then call close when they are all done.
copy.close();

Thanks go out to this tutorial which I eventually found on my own:

http://itextpdf.com/examples/iia.php?id=127