How to edit the contents of an existing PDF programmatically in JAVA

Question

Let's assume I have an existing pdf with a fixed header and footer and blank body like the below image

And I have to add content to the body(white part in the image)

How can I do that in java?

Answer 1

    PdfReader reader = new PdfReader("./the-pdf-where-you-want-to-insert-into.pdf");
    PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("./destination.pdf"));

    PdfReader r = new PdfReader("./the-pdf-you-want-to-insert.pdf");
    PdfImportedPage page = stamper.getImportedPage(r, 1);

    Image instance = Image.getInstance(page);

    AffineTransform at = AffineTransform.getTranslateInstance(x, y); // x y positions where you want insert
    at.concatenate(AffineTransform.getScaleInstance(instance.getScaledWidth(), instance.getScaledHeight()));

    PdfContentByte canvas = stamper.getOverContent(1);
    canvas.addImage(instance, at);

    stamper.close();
    reader.close();