[Java] Add Page Numbers to an Existing PDF document

Page numbers can be used to automatically number each page in documents, and they are usually placed in the header, footer, or side margin. This article will demonstrate how to add page numbers to an existing PDF document at the footer space using a free third-party library called Free Spire.PDFfor Java.

Before running codes, you need to add Spire.Pdf.jar in the library to IDEA. You can download it from the link, or directly refer to it using the following Maven configuration.

<repositories>
<repository>
<id>com.e-iceblue</id>
<name>e-iceblue</name>
<url>http://repo.e-iceblue.com/nexus/content/groups/public/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>e-iceblue</groupId>
<artifactId>spire.pdf.free</artifactId>
<version>3.9.0</version>
</dependency>
</dependencies>

Using the code

import com.spire.pdf.PdfDocument;
import com.spire.pdf.automaticfields.PdfCompositeField;
import com.spire.pdf.automaticfields.PdfPageCountField;
import com.spire.pdf.automaticfields.PdfPageNumberField;
import com.spire.pdf.graphics.*;
import java.awt.*;
import java.awt.geom.Dimension2D;
import java.awt.geom.Rectangle2D;

public class PageNumber {
    public static void main(String[] args) {
        //load a PDF document
        PdfDocument doc = new PdfDocument();
        doc.loadFromFile("C:\\Users\\Test1\\Desktop\\Sample.pdf");

        //create a true type font
        PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Times New Roman", Font.PLAIN, 10));

        //get the page size
        Dimension2D pageSize = doc.getPages().get(0).getSize();

        //declare a float variable
        float y = (float) pageSize.getHeight() - 72;

        //loop through the pages
        for (int i = 0; i < doc.getPages().getCount(); i++) {

            //initialize PdfPageNumberField instance
            PdfPageNumberField number = new PdfPageNumberField();

            //initialize PdfPageCountField instance
            PdfPageCountField count = new PdfPageCountField();

            //create PdfCompositeField instance
            PdfCompositeField compositeField = new PdfCompositeField(font, PdfBrushes.getBlack(), "Page {0} of {1}", number, count);

            //set the text alignment within the composite field
            compositeField.setStringFormat(new PdfStringFormat(PdfTextAlignment.Right, PdfVerticalAlignment.Top));

            //get the text size
            Dimension2D textSize = font.measureString(compositeField.getText());

            //set the position and size of composite field
            compositeField.setBounds(new Rectangle2D.Float((float) pageSize.getWidth() - (float) textSize.getWidth() - 80, y, (float) textSize.getWidth(), (float) textSize.getHeight()));

            //draw composite filed on PDF page
            compositeField.draw(doc.getPages().get(i).getCanvas());
        }

        //save to another file
        doc.saveToFile("output/AddPageNumbers.pdf");
    }
}

Output