如何透过pdfbox及java将多个电子签署加入pdf

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.interactive.digitalsignature.PDSignature;
import org.apache.pdfbox.pdmodel.interactive.digitalsignature.visible.PDVisibleSignDesigner;

import java.io.File;
import java.io.IOException;

public class AddMultipleSignaturesToPDF {
    public static void main(String[] args) {
        try {
            // 加载PDF文件
            PDDocument document = PDDocument.load(new File("input.pdf"));

            // 创建第一个电子签名
            PDPage page1 = document.getPage(0);
            PDVisibleSignDesigner visibleSignDesigner1 = new PDVisibleSignDesigner(document, "image1.png", page1);
            visibleSignDesigner1.xAxis(100).yAxis(100).zoom(0.5f).signatureFieldName("signature1");
            visibleSignDesigner1.buildSignature();

            // 添加第一个电子签名
            PDSignature signature1 = visibleSignDesigner1.getVisibleSignature();
            signature1.setByteRange(new int[]{0, 0, 0, 0});
            signature1.setContents(new byte[]{});

            // 创建第二个电子签名
            PDPage page2 = document.getPage(1);
            PDVisibleSignDesigner visibleSignDesigner2 = new PDVisibleSignDesigner(document, "image2.png", page2);
            visibleSignDesigner2.xAxis(200).yAxis(200).zoom(0.5f).signatureFieldName("signature2");
            visibleSignDesigner2.buildSignature();

            // 添加第二个电子签名
            PDSignature signature2 = visibleSignDesigner2.getVisibleSignature();
            signature2.setByteRange(new int[]{0, 0, 0, 0});
            signature2.setContents(new byte[]{});

            // 保存PDF文件
            document.save("output.pdf");
            document.close();

            System.out.println("电子签名已成功添加到PDF文件中。");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}