java - Tika 检测多部分/签名

Question

我正在使用 Tika 来自动检测被推送到 DMS 中的文档的内容类型。除了电子邮件，几乎所有功能都运行良好。

我必须区分标准邮件消息(mime => message/rfc822)和签名邮件消息(mime => multipart/signed)，但所有电子邮件都被检测为 message/rfc822。

未正确检测到的签名邮件具有以下内容类型 header :

Content-Type: multipart/signed; protocol="application/x-pkcs7-signature"; micalg=sha1; boundary="----4898E6D8BDE1929CA602BE94D115EF4C"

我用来解析的java代码是:

Detector detector;
List<Detector> detectors = new ArrayList<Detector>();
detectors.add(new ZipContainerDetector());
detectors.add(new POIFSContainerDetector());
detectors.add(MimeTypes.getDefaultMimeTypes());
detector = new CompositeDetector(detectors);
String mimetype = detector.detect(TikaInputStream.get(new File(args[0])), new Metadata()).toString();

我正在引用核心库和 tika-parsers 来检测 pdf 和 msword 文档。我还缺少其他东西吗？

Answer 1

我解决了我的问题。我通过实现 Detector 接口(interface)实现了自定义检测器:

public class MultipartSignedDetector implements Detector {

  @Override
  public MediaType detect(InputStream is, Metadata metadata) throws IOException {

    TemporaryResources tmp = new TemporaryResources();

    TikaInputStream tis = TikaInputStream.get(is, tmp);
    tis.mark(Integer.MAX_VALUE);

    try {

      MimeMessage mimeMessage = null;
      String host = "host.com";
      Properties properties = System.getProperties();
      properties.setProperty("mail.smtp.host", host);
      Session session = Session.getDefaultInstance(properties);

      mimeMessage = new MimeMessage(session, tis);

      if(mimeMessage.getContentType() != null && mimeMessage.getMessageID() != null && mimeMessage.getContentType().toLowerCase().contains("multipart/signed"))
        return new MediaType("multipart", "signed");
      else
        return MediaType.OCTET_STREAM;

    } catch(Exception e) {
      return MediaType.OCTET_STREAM;
    } finally {
      try {
        tis.reset();
        tmp.dispose();
      } catch (TikaException e) {
        // ignore
    }
  }
 }
}

然后将自定义检测器添加到复合检测器中，就在默认检测器之前:

Detector detector;
List<Detector> detectors = new ArrayList<Detector>();
detectors.add(new ZipContainerDetector());
detectors.add(new POIFSContainerDetector());

detectors.add(new MultipartSignedDetector());

detectors.add(MimeTypes.getDefaultMimeTypes());
detector = new CompositeDetector(detectors);
String mimetype = detector.detect(TikaInputStream.get(new File(args[0])), new Metadata()).toString();