Firebase Cloud Messaging is the Firebase service that handles push notifications. You can add this service in any client: web, Android or IOS. The specific functioning for each must be read from the documentation.
For adding FCM in any type of project, is always adding a library.
Considering the special support for Android is worthy to take a few lines for it. Create a new project using Android Studio, in the menu go to Tools/Firebase, it will trigger the Firebase assistant. Select "Cloud Messaging" and follow steps one and two.
This is the basis for adding FCM in a project. From this point on, the client is already able to receive FCM push notifications that contain a "notification" payload as long as the app is not in foreground (more details in the remarks).
To further customize the FCM behavior in the client we need to add 2 services, this is well documented in the official site. Again we will take some consideration for Android:
FirebaseMessagingServiceand override the onMessageReceived method
FirebaseInstanceIdServiceand override the onTokenRefresh method
applicationtag </intent-filter> </intent-filter>
You can get the
notification payload and the
data payload inside the
onMessageReceived method using the only argument there. The
onTokenRefresh method is called when the FCM token is assigned by FCM. An FCM token is a unique id for the app installation and the device and can be used as an address of the device to directly send push notifications.
Please read remarks for more information about the types of notification and the associated behavior.