作者：fyupeng
技术专栏：☞ https://github.com/fyupeng
项目地址：☞ https://github.com/fyupeng/distributed-blog-system-api

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留给读者

遇到签名，往往很无奈签名的位置、大小。

一、介绍

直接提供PDF路径和图片路径，以及输出路径，就可以完成需要的需求，关键字也可以作为参数传入，根据自行需求修改。

二、代码

public class PdfBuilderUtil {public static void imageWatermark(String inputPath, String outputPath,String imagePath) throws IOException, com.itextpdf.text.DocumentException {PdfReader reader = new PdfReader(inputPath);PdfStamper stamp = new PdfStamper(reader, new FileOutputStream(outputPath));PdfGState gs1 = new PdfGState();gs1.setFillOpacity(0.1f);InputStream imageIS = new FileInputStream(imagePath);Image image = Image.getInstance(IOUtils.toByteArray(imageIS));int n = reader.getNumberOfPages();InputStream inputStream = new FileInputStream(inputPath);PDDocument document = PDDocument.load(inputStream);for(int i=1;i<=n;i++){PdfContentByte pdfContentByte = stamp.getOverContent(i);// 默认图片水印大小，详见盖章右下角大小样例image.scalePercent(75f);// 默认图片水印横坐标，详见盖章右下角横坐标float absoluteX = 370;// 默认图片水印纵坐标，高度中间位置float absoluteY = (PageSize.POSTCARD.getHeight() - image.getScaledHeight())/2;float[] xyz = getKeyWords(reader, "盖章位置");if (xyz != null && xyz.length >= 3) {//新版文书absoluteY = xyz[1];} else {//旧版文书float[] oldXyz = getKeyWords(reader, "其他位置");if (oldXyz != null && oldXyz.length >= 3) {absoluteY = oldXyz[2]+300;}}// 读取图像文件PDFTextStripper stripper = new PDFTextStripper();stripper.setStartPage(i); // Page indexes are 1-based in PDFTextStripperstripper.setEndPage(i);String text = stripper.getText(document);if (!text.trim().isEmpty()) {image.setAbsolutePosition(absoluteX, absoluteY);pdfContentByte.addImage(image);}}inputStream.close();imageIS.close();stamp.close();reader.close();}/*** 根据关键字定位* @param pdfReader* @param keyWords* @return*/public  static float[] getKeyWords(PdfReader pdfReader, String keyWords) {float[] coordinate = null;int page = 0;try{int pageNum = pdfReader.getNumberOfPages();PdfReaderContentParser pdfReaderContentParser = new PdfReaderContentParser(pdfReader);CustomRenderListener renderListener = new CustomRenderListener();renderListener.setKeyWord(keyWords);for (page = 1; page <= pageNum; page++) {renderListener.setPage(page);pdfReaderContentParser.processContent(page, renderListener);coordinate = renderListener.getPcoordinate();if (coordinate != null) break;}} catch (IOException e) {e.printStackTrace();}return coordinate;}}

pdf签名帮助类

public class CustomRenderListener implements RenderListener{private float[] pcoordinate = null;private String keyWord;private int page;public int getPage() {return page;}public void setPage(int page) {this.page = page;}public float[] getPcoordinate(){return pcoordinate;}public String getKeyWord() {return keyWord;}public void setKeyWord(String keyWord) {this.keyWord = keyWord;}@Overridepublic void beginTextBlock() {}@Overridepublic void endTextBlock() {}@Overridepublic void renderImage(ImageRenderInfo arg0) {}@Overridepublic void renderText(TextRenderInfo textRenderInfo) {String text = textRenderInfo.getText();if (null != text && text.contains(keyWord)) {Float boundingRectange = textRenderInfo.getBaseline().getBoundingRectange();pcoordinate = new float[3];pcoordinate[0] = boundingRectange.x;pcoordinate[1] = boundingRectange.y;pcoordinate[2] = page;}}
}

三、总结

简洁、高效、精炼！