@Override public Component preview() { final Label commonNameLabel = new Label("certCommonName", new Model<String>()); final ByteArrayInputStream certificateStream = new ByteArrayInputStream(uploadedBytes); try { final X509Certificate certificate = (X509Certificate) CertificateFactory.getInstance("X.509").generateCertificate(certificateStream); final StringBuilder commonNameBuilder = new StringBuilder("cn="); final LdapName ldapName = new LdapName(certificate.getIssuerDN().getName()); for (Rdn rdn : ldapName.getRdns()) { if ("CN".equalsIgnoreCase(rdn.getType())) { commonNameBuilder.append( rdn.getValue() == null ? StringUtils.EMPTY : rdn.getValue().toString()); } } commonNameLabel.setDefaultModelObject(commonNameBuilder.toString()); } catch (Exception e) { LOG.error("Error evaluating certificate file", e); throw new IllegalArgumentException("Error evaluating certificate file", e); } finally { IOUtils.closeQuietly(certificateStream); } return this.add(commonNameLabel); }