Apache PDFBox Add Watermark to PDF Document

This tutorial demonstrates how to add a watermark to a PDF document in Java using Apache PDFBox.

Maven Dependencies

We use Apache Maven to manage our project dependencies. Make sure the following dependencies reside on the class-path.

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.8</version>
</dependency>

Apache PDFBox Add Watermark to PDF Document

In this example we add a watermark to an existing PDF document. We use the Overlay class to create an overlay in the background. Finally we save the PDF document.

package com.memorynotfound.pdf.pdfbox;

import org.apache.pdfbox.multipdf.Overlay;
import org.apache.pdfbox.pdmodel.PDDocument;

import java.io.File;
import java.util.HashMap;

public class Watermark {

    public static void main(String[] args) throws Exception{
        PDDocument realDoc = PDDocument.load(new File("/tmp/example.pdf"));

        HashMap<Integer, String> overlayGuide = new HashMap<Integer, String>();
        for(int i=0; i<realDoc.getNumberOfPages(); i++){
            overlayGuide.put(i+1, "/tmp/watermark.pdf");
        }
        Overlay overlay = new Overlay();
        overlay.setInputPDF(realDoc);
        overlay.setOverlayPosition(Overlay.Position.BACKGROUND);
        overlay.overlay(overlayGuide);

        realDoc.save(new File("/tmp/watermarked.pdf"));
    }
}

Demo

When we execute the application, the watermark is applied to the PDF document. You can view the result here. Minor note, for a watermark you should probably be using an image or text with transparent colours.

References

• Apache PdfBox Official Website
• Apache PdfBox API Javadoc
• Overlay JavaDoc