This is a demo Java Spring Boot application to generate FCM notifications. The App uses REST API to send a notification with a random meme embed in it.

Firebase configurations are setup in FirebaseConfig.class, and its implementation is done on FirebaseServiceImpl.java, A Java Bean is already created that will be used to use Firebase Services throughout the Application.

    @Bean
    FirebaseMessaging firebaseMessaging() throws IOException {
        GoogleCredentials googleCredentials = GoogleCredentials
                .fromStream(new ClassPathResource("firebase-service-account.json").getInputStream());
        FirebaseOptions firebaseOptions = FirebaseOptions
                .builder()
                .setCredentials(googleCredentials)
                .build();

        FirebaseApp app = FirebaseApp.initializeApp(firebaseOptions);
        return FirebaseMessaging.getInstance(app);
    }

First, you need atleast JDK 17 or above and Maven installed on your machine.

Then you must provide your Firebase Account Credentials, if you dont have, then generate from firebase.google.com, After getting your own firebase account and credentials of a new project, create a file at /src/main/resources/ called firebase-service-account.json. Then fill the following data with your Firebase account keys.

{
  "type": "your_type",
  "project_id": "your_project_id",
  "private_key_id": "your_private_key_id",
  "private_key": "your_private_key",
  "client_email": "your_client_mail",
  "client_id": "your_client_id",
  "auth_uri": "your_auth_uri",
  "token_uri": "your_token_uri",
  "auth_provider_x509_cert_url": "your_auth_provider_x509_cert_url",
  "client_x509_cert_url": "your_client_x509_cert_url",
  "universe_domain": "your_universal_domain"
}

The App has a public REST API endpoint {DOMAIN}/api/v1/sendNotifications, Method: POST, Request Body: RAW JSON Body of structure:

{
  "fcmToken" : "your_unique_app_device_token_generated_by_firebase"
}

So all the client-app is need to do is sent its fcmToken as a Request Body field into this API to get a random meme notification.

App requires Java 17 or above installed on the machine and uses 2 Dependencies imported from Maven Central called firebase-admin and spring-webflux.

firebase-admin is used to generate and sent push notifications to the located device using FCM TOKEN, and spring-webflux is used to call external APIs, in our case, its used to get a random meme from https://meme-api.com/gimme using GET method.