java PDF添加图层的方法 支持多页图层添加

import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.util.List;import com.itextpdf.text.DocumentException;import com.itextpdf.text.Image;import com.itextpdf.text.pdf.PdfContentByte;import com.itextpdf.text.pdf.PdfReader;import com.itextpdf.text.pdf.PdfStamper;public class PdfUtils { /**  * PDF添加图层  *   * @param srcPdf  *   原PDF文件路径  * @param distPdf  *   合成PDF输出路径  * @param layerPathArr  *   图层路径列表，图层名称需为数字(按照图片名称数字顺序合成在PDF对应页数上)  * @return  * @throws IOException  * @throws DocumentException  */ public static String markLocalImage42Dist(String srcPdf, String distPdf, List<String> layerPathArr)   throws IOException, DocumentException {   File srcPdfFile = new File(srcPdf);   if (!srcPdfFile.exists()) {    throw new IllegalArgumentException("找不到需要添加图层的pdf文件");   }   PdfReader reader = new PdfReader(srcPdf);   int n = reader.getNumberOfPages(); // PDF页数   PdfStamper stamp = new PdfStamper(reader, new FileOutputStream(distPdf));   PdfContentByte over;   for (String layerPath : layerPathArr) {    File layerFile = new File(layerPath);    String currentPageNo = layerFile.getName().substring(0, layerFile.getName().lastIndexOf(".")); // 图片名称(对应页数)    boolean isNum = currentPageNo.matches("[0-9]+");    if (!isNum) {     throw new IllegalArgumentException("图层名称是不是数字");    }    Image img = Image.getInstance(layerPath);    img.setAbsolutePosition(0, 0);    if (n > 0 && n >= Integer.parseInt(currentPageNo)) {     over = stamp.getOverContent(Integer.parseInt(currentPageNo));     over.addImage(img);    }   }   stamp.close();   reader.close();  return distPdf; }}

public static void main(String[] args) throws IOException, DocumentException {  List<String> imgUrlList = new ArrayList<>();  imgUrlList.add("D:/ts/testPDF/1.png");  //imgUrlList.add("D:/ts/testPDF/2.png");  imgUrlList.add("D:/ts/testPDF/3.png");  markLocalImage42Dist("D:/ts/testPDF/testPDF.pdf", "D:/ts/testPDF/testPDF2.pdf", imgUrlList); }