从PDF签章文件中提取印章以及印章图片

2024-01-26 15:10| 来源: 网络整理| 查看: 265

1.SM2签章

2.RSA签章

1.SM2签章

国密签章是有签章结构的，遵循一定的标准，可以从签章结构中解析出印章，然后再从印章中保存图片

代码如下：

public void getSealFromPDFStamp() throws Exception { String pdfStampPath = "F:/Netseal_Work/签章项目和主线总结/离职证明/适配子公司UKEY/上海信旋/安印工具签章.pdf"; byte[] pdfData = FileUtil.getFile(pdfStampPath); PdfReader reader = null; try { reader = new PdfReader(pdfData); AcroFields af = reader.getAcroFields(); ArrayList names = af.getSignatureNames(); // 获取每一个签名域的 Contents for (String name : names) { PdfDictionary dictionary = af.getSignatureDictionary(name); byte[] bytes = dictionary.getAsString(PdfName.CONTENTS).getBytes(); String hexContents = HexUtil.byte2Hex(bytes); while (hexContents.endsWith("00")) hexContents = hexContents.substring(0, hexContents.length() - 2); StampData sd = new StampData(bytes); byte[] stampData = sd.getEseal().getEncoded(); FileUtil.storeFile("E:/1.asn1",stampData); } } catch (Exception e) { throw e; } finally { try { if (reader != null) reader.close(); } catch (Exception e) { } } }

解析保存下来的文件用asn1工具打开

将图片数据保存成文件，就可以把印章图片提取出来了

2.RSA签章

RSA签章没有签章结构，笼统意义来说就是加盖图片进行签名，所以不能再用上面的方式进行提取印章图片，使用PDF源码进行提取

public PdfImageObject extractImage(String signatureName) throws Exception { MyImageRenderListener listener = new MyImageRenderListener(); PdfDictionary sigFieldDic = reader.getAcroFields().getFieldItem(signatureName).getMerged(0); PdfDictionary appearancesDic = sigFieldDic.getAsDict(PdfName.AP); PdfStream normalAppearance = appearancesDic.getAsStream(PdfName.N); PdfDictionary resourcesDic = normalAppearance.getAsDict(PdfName.RESOURCES); PdfContentStreamProcessor processor = new PdfContentStreamProcessor(listener); processor.processContent(ContentByteUtils.getContentBytesFromContentObject(normalAppearance), resourcesDic); return listener.image; }

public static void main(String[] args) throws Exception { byte[] pdfData = FileUtil.getFile("F:/Netseal_Work/签章项目和主线总结/离职证明/适配子公司UKEY/上海信旋/安印工具签章.pdf"); PdfReader reader = new PdfReader(pdfData); AcroFields acroFields = reader.getAcroFields(); List names = acroFields.getSignatureNames(); ExtractPhoto ep = new ExtractPhoto(reader); for (String name : names) { PdfImageObject image = ep.extractImage(name); FileUtil.storeFile("f:/temp/pdf/" + name + ".png", image.getImageAsBytes()); } reader.close(); } }

注意：解析出来的图片带背景，一般都是白色背景，然后再进行一次去背景的操作

public static byte[] cleanBGColor(byte[] bs) throws Exception { ByteArrayInputStream bais = new ByteArrayInputStream(bs); BufferedImage bi = ImageIO.read(bais); BufferedImage tmp = new BufferedImage(bi.getWidth(), bi.getHeight(), BufferedImage.TYPE_4BYTE_ABGR); for (int i = 0, width = bi.getWidth(); i < width; i++) { for (int j = 0, height = bi.getHeight(); j < height; j++) { int rgb = bi.getRGB(i, j); // if (((rgb & 0xff000000) >> 24 & 0xff) > 0x80) // tmp.setRGB(i, j, rgb); // else // tmp.setRGB(i, j, Color.WHITE.getRGB()); byte[] d = HexUtil.int2Byte(rgb); int a = d[0] & 0xff; int r = d[1] & 0xff; int g = d[2] & 0xff; int b = d[3] & 0xff; if (r == 255 && g == 255 && b == 255) { d[0] = 0; rgb = HexUtil.byte2Int(d); } tmp.setRGB(i, j, rgb); } } ByteArrayOutputStream baos = new ByteArrayOutputStream(); ImageIO.write(tmp, "png", baos); return baos.toByteArray(); }

以上步骤就可以获取RSA签章文件的印章图片了

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