iTextPDF签名:如何不显示签名字段，而是显示图像

Question

我使用itextpdf-5来签署PDF。我想签署文件，但使所有字段(原因，位置)都不可见，除了图像。我可以在第三方程序中这样做(我附上这样一个PDF的示例:签名存储所有数据，但不显示)。在我的程序中，我没有在文档中找到这样的东西(我正在附上代码示例)。

包含隐藏数据的示例PDF

 private static void emptySignature(String src, String dest, String sigName, int page, int x, int y) {
    try {
        Image image = Image.getInstance(new File(currentPatient.getCurrentSign().getLocalFilePath()).toURL());;
        PdfReader reader = new PdfReader(src);
        FileOutputStream os = new FileOutputStream(dest);
        PdfStamper stamper = PdfStamper.createSignature(reader,os,'\0',new File("data/results/temp"),true);

        PdfSignatureAppearance appearance = stamper.getSignatureAppearance();
        appearance.setVisibleSignature(new Rectangle(x,y,x+80,y-60),page,sigName); 
        //Hide it!
        appearance.setReason("Nikita");
        appearance.setLocation("Sanitas");
        //No hide
        appearance.setImage(image);

        ExternalSignatureContainer external = new ExternalBlankSignatureContainer(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
        MakeSignature.signExternalContainer(appearance,external,8192);
        os.close();
        reader.close();
        stamper.close();
    } catch (Exception ex) {}
}

Answer 1

PdfSignatureAppearance有一个带有RenderingMode参数的setter setRenderingMode。RenderingMode是具有以下值的枚举：

public enum RenderingMode {
    /**
     * The rendering mode is just the description.
     */
    DESCRIPTION,
    /**
     * The rendering mode is the name of the signer and the description.
     */
    NAME_AND_DESCRIPTION,
    /**
     * The rendering mode is an image and the description.
     */
    GRAPHIC_AND_DESCRIPTION,
    /**
     * The rendering mode is just an image.
     */
    GRAPHIC
}

因此，要使除图像以外的所有字段(原因、位置)都不可见，只需将呈现模式设置为GRAPHIC。

appearance.setRenderingMode(RenderingMode.GRAPHIC);