使用 pdfbox 1.8.8 进行视觉签名

我正在尝试生成带有视觉签名和 pdfbox 的 PDF。我有两个流，似乎 pdfbox 只能处理文件。如果没有三个临时文件，我就无法使其工作。我可以看到从here https://github.com/apache/pdfbox/blob/b789c91d57f4a3b8763b35779309ea422db66c5d/examples/src/main/java/org/apache/pdfbox/examples/signature/CreateSignature.java该 API 已更改，但它仍然处理文件。

public void signPdf(InputStream originalPdf, OutputStream signedPdf,
        InputStream image, float x, float y,
        String name, String location, String reason) {

    File temp = null;
    File temp2 = null;
    File scratchFile = null;
    RandomAccessFile randomAccessFile = null;
    OutputStream tempOut = null;
    InputStream tempIn = null;
    try {
        /* Copy original to temporary file */
        temp = File.createTempFile("signed1", ".tmp");
        tempOut = new FileOutputStream(temp);
        copyStream(originalPdf, tempOut);
        tempOut.close();

        /* Read temporary file to second temporary file and stream */
        tempIn = new FileInputStream(temp);
        temp2 = File.createTempFile("signed2", ".tmp");
        tempOut = new FileOutputStream(temp2);
        copyStream(tempIn, tempOut);
        tempIn.close();
        tempIn = new FileInputStream(temp2);

        scratchFile = File.createTempFile("signed3", ".bin");
        randomAccessFile = new RandomAccessFile(scratchFile, "rw");

        /* Read temporary file */
        PDDocument document = PDDocument.load(temp, randomAccessFile);
        document.getCurrentAccessPermission().setCanModify(false);

        PDSignature signature = new PDSignature();
        signature.setFilter(PDSignature.FILTER_ADOBE_PPKLITE);
        signature.setSubFilter(PDSignature.SUBFILTER_ADBE_PKCS7_DETACHED);
        signature.setName(name);
        signature.setLocation(location);
        signature.setReason(reason);
        signature.setSignDate(Calendar.getInstance());

        PDVisibleSignDesigner signatureDesigner = new PDVisibleSignDesigner(
                document, image, document.getNumberOfPages());
        signatureDesigner.xAxis(250).yAxis(60).zoom(-90).signatureFieldName("signature");

        PDVisibleSigProperties signatureProperties = new PDVisibleSigProperties();
        signatureProperties.signerName(name).signerLocation(location)
                .signatureReason(reason).preferredSize(0).page(1)
                .visualSignEnabled(true).setPdVisibleSignature(signatureDesigner)
                .buildSignature();

        SignatureOptions options = new SignatureOptions();
        options.setVisualSignature(signatureProperties);

        document.addSignature(signature, dataSigner, options);

        /* Sign */
        document.saveIncremental(tempIn, tempOut);
        document.close();
        tempIn.close();

        /* Copy temporary file to an output stream */
        tempIn = new FileInputStream(temp2);
        copyStream(tempIn, signedPdf);
    } catch (IOException e) {
        logger.error("PDF signing failure", e);
    } catch (COSVisitorException e) {
        logger.error("PDF creation failure", e);
    } catch (SignatureException e) {
        logger.error("PDF signing failure", e);
    } finally {
        closeStream(originalPdf);
        closeStream(signedPdf);
        closeStream(randomAccessFile);
        closeStream(tempOut);
        deleteTempFile(temp);
        deleteTempFile(temp2);
        deleteTempFile(scratchFile);
    }
}

private void deleteTempFile(File tempFile) {
    if (tempFile != null && tempFile.exists() && !tempFile.delete()) {
        tempFile.deleteOnExit();
    }
}

private void closeStream(Closeable is) {
    if (is!= null) {
        try {
            is.close();
        } catch (IOException e) {
            logger.error("failure", e);
        }
    }
}

private void copyStream(InputStream is, OutputStream os) throws IOException {
    byte[] buffer = new byte[1024];
    int c;
    while ((c = is.read(buffer)) != -1) {
        os.write(buffer, 0, c);
    }
    is.close();
}

除了文件疯狂之外，我在签名上没有看到任何文字。结果如下：

当我使用 itext 库做类似的事情时，这就是它的样子

为什么视觉签名表示中缺少名称、位置和原因？我该如何解决这个问题？

为什么视觉签名表示中缺少名称、位置和原因？

它们不存在是因为它们没有被绘制。

iText 表示可视化签名的默认方式是将这些信息添加到可视化中。

PDFBox的默认方式'PDVisibleSigBuilder表示可视化签名没有这样的信息。

两者都没有错或对，两者都只是默认值。

毕竟，人们查找此类信息的规范位置是签名面板。

我该如何解决这个问题？

签名可视化的实际内容是由PDVisibleSigBuilder期间的实例signatureProperties.buildSignature():

public void buildSignature() throws IOException
{
    PDFTemplateBuilder builder = new PDVisibleSigBuilder();
    PDFTemplateCreator creator = new PDFTemplateCreator(builder);
    setVisibleSignature(creator.buildPDF(getPdVisibleSignature()));
}

因此，通过替换

    signatureProperties.signerName(name).signerLocation(location)
            .signatureReason(reason).preferredSize(0).page(1)
            .visualSignEnabled(true).setPdVisibleSignature(signatureDesigner)
            .buildSignature();

在你的代码中

    signatureProperties.signerName(name).signerLocation(location)
            .signatureReason(reason).preferredSize(0).page(1)
            .visualSignEnabled(true).setPdVisibleSignature(signatureDesigner);

    PDFTemplateBuilder builder = new ExtSigBuilder();
    PDFTemplateCreator creator = new PDFTemplateCreator(builder);
    signatureProperties.setVisibleSignature(creator.buildPDF(signatureProperties.getPdVisibleSignature()));

定制版本ExtSigBuilder这个的PDVisibleSigBuilder类，你可以在那里画任何你想要的东西，例如：

class ExtSigBuilder extends PDVisibleSigBuilder
{
    String fontName;

    public void createImageForm(PDResources imageFormResources, PDResources innerFormResource,
            PDStream imageFormStream, PDRectangle formrect, AffineTransform affineTransform, PDJpeg img)
            throws IOException
    {
        super.createImageForm(imageFormResources, innerFormResource, imageFormStream, formrect, affineTransform, img);

        PDFont font = PDType1Font.HELVETICA;
        fontName = getStructure().getImageForm().getResources().addFont(font);

        logger.info("Added font to image form: " + fontName);
    }

    public void injectAppearanceStreams(PDStream holderFormStream, PDStream innterFormStream, PDStream imageFormStream,
            String imageObjectName, String imageName, String innerFormName, PDVisibleSignDesigner properties)
            throws IOException
    {
        super.injectAppearanceStreams(holderFormStream, innterFormStream, imageFormStream, imageObjectName, imageName, innerFormName, properties);

        String imgFormComment = "q " + 100 + " 0 0 50 0 0 cm /" + imageName + " Do Q\n";
        String text = "BT /" + fontName + " 10 Tf (Hello) Tj ET\n";
        appendRawCommands(getStructure().getImageFormStream().createOutputStream(), imgFormComment + text);

        logger.info("Added text commands to image form: " + text);
    }
}

在图像表单（实际显示某些内容的表单）左下角上方以 10 号的 Helvetica 格式写下“Hello”。

PS：我认为这背后的面向对象结构应该彻底改革。