Code sample to create CA bundle in PEM format in Android

gistfile1.txt

public void getCertificateBundle() {
        TrustManager managers[]= {null};
        TrustManagerFactory tmf = null;

        try {
            tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

        try {
            tmf.init((KeyStore) null);
        } catch (KeyStoreException e) {
            e.printStackTrace();
        }

        managers = tmf.getTrustManagers();
        StringWriter sw = new StringWriter();

        for (int i = 0; i < managers.length; i++) {
            if (managers[i] instanceof X509TrustManager) {
                X509TrustManager trustMgr = (X509TrustManager) managers[i];
                X509Certificate[] certificates = trustMgr.getAcceptedIssuers();
                
                for (int j = 0; j < certificates.length; j++) {
                    try {
                        sw.write("-----BEGIN CERTIFICATE-----\n");
                        sw.write(Base64.encodeToString(certificates[j].getEncoded(), Base64.DEFAULT));
                        sw.write("-----END CERTIFICATE-----\n");
                    } catch (CertificateEncodingException e) {
                        Log.e(TAG, "Encoding error");
                        e.printStackTrace();
                    }
                }
            }
        }
        PrintWriter writer = null;
        try {
            writer = new PrintWriter(Environment.getExternalStorageDirectory() + File.separator + "bundle.crt", "UTF-8");
            writer.print(sw.toString());
            writer.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }