Android推送通知教程：如何将通知发送给“关注者”？

Question

I have written a test app where users can publish some data (location, photos, tags etc.) to their "feed" (ie write some data to an online database which is currently Firebase). If other users are "following" this user (or a relevant tag), how do I send notifications to the followers that new data is available?

I have looked at Google Cloud Messaging and the replacement Firebase Cloud Messaging, but I find their documentation too technical for me (seems aimed towards IT professionals). I can program but don't really understand "servers", "protocols" etc. It seems from GCM/FCM docs I need a "server" before I can use their services. This server will

• Recognise when a database event happens.

• Run some logic to ascertain whether notifications need to be sent out (and to whom)

• Inform GCM or FCM to do so.

Is this correct? If so I don't know how to get a server, write one, plug one in or whatever it is I'm supposed to do with one. Any advise or simple tutorials that anyone can give a neophyte developer is greatly appreciated!

Thanks, Riz

Answer 1

It seems you're trying to implement GCM Topic Messaging where your app server sends messages to mulitple devices that are subscribed to a particular "topic". Though this particular feature doesn't seem to be that feasible, it is doable.

Before your followers can get notified, they must first be subscribed to a topic.

Here's how to subscirbe in Android:

private void subscribeTopics(String token) throws IOException {
    GcmPubSub pubSub = GcmPubSub.getInstance(this);
    for (String topic : TOPICS) {
        pubSub.subscribe(token, "/topics/" + topic, null);
    }
}

Try this actual demos to get a grip on this:

GCM Playground - A reference implementation of a GCM Application Server in the form of a playground that developers can use to test the Google Cloud Messaging Service.

Since Google now encourages users to use FCM, try the FCM Android Quickstart . You can also read through this SO post for additional insight.