X509Certificate cert = (X509Certificate) CertificateFactory.getInstance("X.509")
    .generateCertificate(new FileInputStream("cert.cer"));

  Asn1BerDecodeBuffer buffer = new Asn1BerDecodeBuffer(cert.getEncoded());
  Certificate certAsn = new Certificate();

  certAsn.decode(buffer);
  Extensions extensions = certAsn.tbsCertificate.extensions;

  final int[] caIssuer = {1, 3, 6, 1, 5, 5, 7, 1, 1};
  final int[] ocspExtensionOid = {1, 3, 6, 1, 5, 5, 7, 48, 1};

  List<String> urls = new ArrayList<>(2);
  for (Extension extension : extensions.elements) {

    if (Arrays.equals(extension.extnID.value, caIssuer)) {

      buffer.reset();
      buffer = new Asn1BerDecodeBuffer(extension.extnValue.value);

      AuthorityInfoAccessSyntax accessSyntax = new AuthorityInfoAccessSyntax();
      accessSyntax.decode(buffer);

      for (AccessDescription accessDescription : accessSyntax.elements) {

        if (Arrays.equals(accessDescription.accessMethod.value, ocspExtensionOid)) {

          if (accessDescription.accessLocation.getChoiceID() == GeneralName._UNIFORMRESOURCEIDENTIFIER) { // URL

            Asn1IA5String name = (Asn1IA5String) accessDescription.accessLocation.getElement();
            urls.add(name.value);

          } // if

        } // if

      } // for

    } // if

  } // for

  System.out.println("%%% URLs %%%");

  for (String url : urls) {
    System.out.println(url);
  } // for