如何使用iText在文本下插入图像作为PDF背景？

   <groupId>com.itextpdf</groupId>
   <artifactId>itextpdf</artifactId>
   <version>5.5.13.2</version>
</dependency>

import com.itextpdf.text.*;
import com.itextpdf.text.pdf.*;
import java.io.*;

public static void createPdfWithBackgroundImage(String imagePath, String outputPath) throws DocumentException, IOException {
    // Your code will go here
}

Document document = new Document();

PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(outputPath));

PdfContentByte canvas = writer.getDirectContent();

Image background = Image.getInstance(imagePath);

background.setAbsolutePosition(0, 0);
background.scaleAbsolute(PageSize.A4.getWidth(), PageSize.A4.getHeight());

canvas.addImage(background);

document.setPageSize(PageSize.A4);

document.open();
document.add(new Paragraph("This text will be placed on top of the background image."));
document.close();