Android gets signing certificate information

 Obtain the signature certificate information in the above decompiled apk.

 public static StringBuffer getCert(Activity activity) {
        PackageManager pm = activity.getPackageManager();
        StringBuffer sb = new StringBuffer();
        try {
            PackageInfo info = pm.getPackageInfo(activity.getPackageName(), activity.getPackageManager().GET_SIGNATURES);
            Signature[] sigs = info.signatures;
            for (Signature sig : sigs) {
                final byte[] rawCert = sig.toByteArray();
                InputStream certStream = new ByteArrayInputStream(rawCert);

                final CertificateFactory certFactory;
                final X509Certificate x509Cert;

                try {
                    certFactory = CertificateFactory.getInstance("X509");
                    x509Cert = (X509Certificate) certFactory.generateCertificate(certStream);

                    sb.append("Certificate subject:" + x509Cert.getSubjectDN() + "\n\n");
                    sb.append("Certificate issuer:" + x509Cert.getIssuerDN() + "\n\n");
                    sb.append("Cretificate serival number:" + x509Cert.getSerialNumber() + "\n\n");

                } catch (Exception e) {
                    //e.printStackTrace();
                }

            }
        } catch (PackageManager.NameNotFoundException e) {
            //e.printStackTrace();
        }
        return sb;
    }