Retrieve JWT Authentication Access Token Using HttpsURLConnection

In JWT Authentication, a token is used to access the API interfaces.  In general, it will be a two-step authentication process. First, it will authenticate the user using the user's credentials such as login id, password, client id, and secret keys. Following is a method on how to get the access token uses HTTPS protocol.

    public JwtAuthenticationResponse getHttpsAuthToken(String hostName, int port,     

                                                                    String   userName, String userPassword,

                                                            String grantType, String clientId, String clientSecret,

                                                               String urlPath) 

        HttpsURLConnection httpConn = null;

        final int BUFFER_SIZE = 4096;

        // Create a trust manager that does not validate certificate chains (should be removed in prod env)

        TrustManager[] trustAllCerts = new TrustManager[]{new X509TrustManager() {

            public java.security.cert.X509Certificate[] getAcceptedIssuers() {

                return null;

            }

            public void checkClientTrusted(X509Certificate[] certs, String authType) {

            }

            public void checkServerTrusted(X509Certificate[] certs, String authType) {

            }

        }

        };

        try {

            // Install the all-trusting trust manager

            SSLContext sc = SSLContext.getInstance("SSL");

            sc.init(null, trustAllCerts, new java.security.SecureRandom());

            HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());

            // Create all-trusting host name verifier

            HostnameVerifier allHostsValid = new HostnameVerifier() {

                public boolean verify(String hostname, SSLSession session) {

                    return true;

                }

            };

            HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);

        } catch (NoSuchAlgorithmException e) {

            logger.debug(String.format("Cannot connect to Hybris server:  %s ;", e.toString()));

            throw new RuntimeException(e);

        } catch (KeyManagementException e) {

            logger.debug(String.format("Cannot connect to Hybris server:  %s ;", e.toString()));

            throw new RuntimeException(e);

        }

        String url;

url = "https://"+hostName + ":"+String.valueOf(port)+"/services/oauth2/token";

        logger.debug("get authendication using: " + url);

        InputStream inputStream;

        try {

            StringBuilder data = new StringBuilder ( );

            data.append ("grant_type=" + grantType);

            data.append ("&client_id=" + clientId);

            data.append ("&client_secret=" + clientSecret);

            if (userId != null && !userId.equals ("undefined")) {

                data.append ("&username=" + userId);

            }

            if (userPassword != null && !userPassword.equals ("undefined")) {

                data.append ("&password=" + userPassword);

            }

           String auth = clientId + ":" + clientSecret;

            byte[] encodedS = Base64.encodeBase64 (auth.getBytes ( ));

            String authHeader = "Basic " + new String (encodedS);

            // Create a byte array of the data to be sent

            byte[] encodedAuth = data.toString ( ).getBytes ("UTF-8");

            String authId = userId + ":" + userPassword;

            byte[] encodedId = Base64.encodeBase64 (authId.getBytes ( ));

            String authHeaderId = "Basic " + new String (encodedId);

            // Setup the Request

            URL request = new URL (url);

            httpConn = (HttpsURLConnection) request.openConnection ( );

            httpConn.setRequestMethod ("POST");

            httpConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

            httpConn.setRequestProperty("Content-Length", "" + encodedAuth.length);

            httpConn.setRequestProperty("Content-Length", "" + encodedAuth.length);

            httpConn.setRequestProperty("Authorization", authHeaderId);

            httpConn.setUseCaches (false);

            httpConn.setDoOutput (true);

            // Write data

            OutputStream postStream = httpConn.getOutputStream ( );

            postStream.write (encodedAuth);

            postStream.flush ( );

            postStream.close ( );

            // For POST only - END

            int responseCode = httpConn.getResponseCode ( );

            String response;

            if (responseCode == 200) {

                inputStream = httpConn.getInputStream ( );

                ObjectMapper mapper = new ObjectMapper ( );

                JsonNode jsonMap = mapper.readTree (inputStream);

                String token = jsonMap.get ("access_token").toString ( ).replaceAll ("\"", "");

                String tokenType = jsonMap.get ("token_type").toString ( ).replaceAll ("\"", "");

                String refreshToken = null;

                return new JwtAuthenticationResponse (jsonMap.get ("access_token").toString ( ));

            } else {

                inputStream = httpConn.getErrorStream ( );

                try (Scanner scanner = new Scanner (inputStream)) {

                    scanner.useDelimiter ("\\Z");

                    response = (scanner.next ( ));

             }

            String exceptionMsg = "Response Code " + String.valueOf (responseCode) + ". " +

                                                  response;

                throw new UserDefinedException (exceptionMsg);

            }

        } catch (IOException | UserDefinedException e) {

            logger.debug(String.format("Cannot connect to server:  %s ;", e.toString()));

            throw new RuntimeException(e);

        }

    }