Scale an existing page about pdfbox-graphics2d HOT 2 CLOSED

 public void scale() throws IOException {
        PDDocument document = PDDocument.load(pdf);

            PDPage page =  document.getPage(0);
            PDPageContentStream contentStreamBefore = new PDPageContentStream(document, page, AppendMode.Prepend, true);
       
            Matrix matrix = new Matrix();
            float xScale = PDRectangle.A4.getWidth() / page.getMediaBox().getWidth();
            float yScale = PDRectangle.A4.getHeight() / page.getMediaBox().getHeight();
            matrix.scale(xScale, yScale);

            contentStreamBefore.transform(matrix);
            contentStreamBefore.close();

        document.save(pdf);
        document.close();
    }