pdfbox 标志错误文档已被更改或损坏

如何解决pdfbox 标志错误文档已被更改或损坏

这是我在 git 中的项目：https://github.com/phuclv3/sign_nature.git 请帮帮我！！！

我已经用下面的代码实现了pdf文件哈希的数字签名功能：

// Generate pdf hash file
public static byte[] getPdfBytesToSign(File pdf,PDSignature signature,HashAlgorithm hashAlg,String password,PDVisibleSigProperties visibleSignatureProperties) throws Exception {
    PDDocument doc = null;
    File pdfTempFile = null;
    try {
        if (password == null) {
            doc = PDDocument.load(pdf);
        } else {
            doc = PDDocument.load(pdf,password);
        }
        final MessageDigest digest = MessageDigest.getInstance(hashAlg.getValue());
        SignatureInterface signatureInterface = new SignatureInterface() {
            @Override
            public byte[] sign(InputStream content) throws IOException {
                digest.update(IoUtils.toByteArray(content));
                return digest.digest();
            }
        };
        SignatureOptions signatureOptions = new SignatureOptions();
        if (visibleSignatureProperties != null) {
            signatureOptions.setVisualSignature(visibleSignatureProperties);
            signatureOptions.setPage(visibleSignatureProperties.getPage() - 1);
        }
        // Add signature
        doc.addSignature(signature,signatureInterface,signatureOptions);
        // Create output stream
        pdfTempFile = File.createTempFile("chars",String.valueOf(Calendar.getInstance().getTimeInMillis()));
        OutputStream fos = new FileOutputStream(pdfTempFile);
        if (doc.getDocumentId() == null) {
            doc.setDocumentId(0L);
        }
        // Fire method in signature inteface
        doc.saveIncremental(fos);

        return digest.digest();
    } catch (Exception ex) {
        ex.printstacktrace();
        throw ex;
    } finally {
        doc.close();
        if (pdfTempFile != null)
            FileUtils.deleteQuietly(pdfTempFile);
    }
}

这是剩下的

// this method attachedPdfSignature

public static void attachPdfSignature(File pdfInput,byte[] signedByte,PDVisibleSigPropertiesvisibleSignatureProperties,OutputStream pdfOutput) 抛出异常 { PDDocument 文档 = 空； 尝试 { 如果（密码==空）{ doc = PDDocument.load(pdfInput); } 别的 { doc = PDDocument.load(pdfInput,密码);

        }
        doc.getDocument().getTrailer().removeItem(COSName.TYPE);

        SignatureInterface signatureInterface = new SignatureInterface() {
            @Override
            public byte[] sign(InputStream content) throws IOException {
                return signedByte;
            }
        };
        // register signature dictionary and sign interface
        SignatureOptions signatureOptions = new SignatureOptions();

        if (visibleSignatureProperties != null) {
            signatureOptions.setVisualSignature(visibleSignatureProperties);
            signatureOptions.setPage(visibleSignatureProperties.getPage() - 1);
        }
        // Assign signature
        doc.addSignature(signature,signatureOptions);
        // Fire method in signature interface
        doc.setDocumentId(0L);
        doc.saveIncremental(pdfOutput);
    } catch (Exception ex) {
        ex.printstacktrace();
        throw ex;
    } finally {
        doc.close();
    }
}

签名后，签名无效如下：