Android Push Template

Author: Daniel Passos (dpassos@redhat.com)
Level: Intermediate
Technologies: Java, Android, RHMAP, FCM Push Messages
Summary: A demonstration of how to receive a GCM push message from RHMAP
Community Project : Feed Henry
Target Product: RedHat Mobile Application Platform aka RHMAP
Product Versions: RHMAP 3.8.0+
Source: https://github.com/feedhenry-templates/pushstarter-android-app
Prerequisites: fh-android-sdk: 4.0.+, Android Studio: 3.0.0 or newer, Android SDK: 26+ or newer

What is it?

This application will subscribe to a push service running in a RHMAP instance. The user can send messages to the device using RHMAP and view them on the device.

If you do not have access to a RHMAP instance, you can sign up for a free instance at https://openshift.feedhenry.com/.

How do I run it?

RHMAP Studio

You can create this project as a template inside of RHMAP Studio. The full tutorial for setting up AeroGear UPS, registering on the Google Cloud Messaging network, and using the app can be found on the RedHat Mobile docs site.

Firebase Cloud Messaging

You need to have a valid Firebase Cloud Messaging project setup. Download the google-services.json file from the Firebase Console and put it into the app directory of your Android Application.
You also need to use the package from the Firebase Cloud Messaging configuration as the package for your application.

Build instructions for Open Source Development

If you wish to contribute to this template, the following information may be helpful; otherwise, RHMAP and its build facilities are the preferred solution.

Build instructions

Edit app/src/main/assets/fhconfig.properties to include the relevant information from RHMAP.
Attach running Android Device with API 16+ running
./gradlew installDebug

How does it work?

Registration With Messaging Services

In app/src/main/java/org/feedhenry/pushstarter/activities/RegisterActivity.java there is the following block of code :

FH.pushRegister(new FHActCallback() {
            @Override
            public void success(FHResponse fhResponse) {
                startActivity(new Intent(RegisterActivity.this, MessagesActivity.class));
            }

            @Override
            public void fail(FHResponse fhResponse) {
                Toast.makeText(getApplicationContext(),
                        fhResponse.getErrorMessage(), Toast.LENGTH_SHORT).show();
                finish();
            }
        });

This code will register the device with both AeroGear UnifiedPush Service AND Google's GCM network. If both actions are successful then it will launch the main activity. Otherwise it will display an error and quit.

Handling messages

Messages are handled by implementations of the MessageHandler interface which are registered with the RegistrarManager. These classes are /app/src/main/java/org/feedhenry/pushstarter/activities/MessagesActivity.java and app/src/main/java/org/feedhenry/pushstarter/handler/NotificationBarMessageHandler.java.

In the MessagesActivity class the Activity switches between itself and the NotificationBarMessageHandler in the onPause and onResume methods.

 @Override
    protected void onResume() {
        super.onResume();
        RegistrarManager.registerMainThreadHandler(this);
        RegistrarManager.unregisterBackgroundThreadHandler(NotificationBarMessageHandler.instance);

        displayMessages();
    }

    @Override
    protected void onPause() {
        super.onPause();
        RegistrarManager.unregisterMainThreadHandler(this);
        RegistrarManager.registerBackgroundThreadHandler(NotificationBarMessageHandler.instance);
    }