แก้ไขไฟล์ PDF ผ่าน Java

    Document doc = new Document("sourceFile.pdf");

    Rectangle rect = new Rectangle(200, 500, 300, 600);
    RedactionAnnotation annot = new RedactionAnnotation(doc.getPages().get_Item(1), rect);

    annot.setFillColor(Color.getBlack());
    annot.setBorderColor(Color.getYellow());
    annot.setColor(Color.getBlue());
    annot.setFontSize(20);
    annot.setOverlayText("REDACTED");
    annot.setTextAlignment(HorizontalAlignment.Center);
    annot.setRepeat(true);
    
    doc.getPages().get_Item(1).getAnnotations().add(annot);
    doc.save("output.pdf");