AndroidのPush通知(FCM)をサーバー知識無しで試してみよう ref: https://qiita.com/flatfisher/items/bdec83caf3c7f9c8917c

AndroidManifest.xml

<application>
   <service
       android:name=".MyFcmListenerService">
       <intent-filter>
           <action android:name="com.google.firebase.MESSAGING_EVENT" />
       </intent-filter>
   </service>
<application/>

build.gradle

dependencies {
  compile "com.google.firebase:firebase-messaging:10.2.4"
}

// ファイルの一番下に追加
apply plugin: 'com.google.gms.google-services'

Linux

keytool -exportcert -list -v \
-alias androiddebugkey -keystore ~/.android/debug.keystore

Logcat

MyInstanceIDListenerService: Refreshed token: xxxxxxxxxxxxxxxxxxxxx

MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import com.google.firebase.messaging.FirebaseMessaging;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Push通知の購読開始
        FirebaseMessaging.getInstance().subscribeToTopic("mytopic");

        //購読解除
        FirebaseMessaging.getInstance().unsubscribeFromTopic("mytopic");
    }
}

MyFcmListenerService.java

import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.media.RingtoneManager;
import android.net.Uri;
import android.support.v4.app.NotificationCompat;
import android.util.Log;

import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

import java.util.Map;

public class MyFcmListenerService extends FirebaseMessagingService {

    private final static String TAG = MyFcmListenerService.class.getSimpleName();

    @Override
    public void onMessageReceived(RemoteMessage message){
        String from = message.getFrom();
        Map data = message.getData();

        Log.d(TAG, "from:" + from);
        Log.d(TAG, "data:" + data.toString());

        String msg = data.get("data").toString();
        sendNotification(msg);
    }

    private void sendNotification(String message) {
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this,0 , intent,
                PendingIntent.FLAG_ONE_SHOT);

        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentTitle("Push通知のタイトル")
                .setSubText("Push通知のサブタイトル")
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setStyle(new NotificationCompat.BigTextStyle().bigText(message))
                .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(0 , notificationBuilder.build());
    }
}

MyInstanceIDListenerService.java

import android.util.Log;

import com.google.firebase.iid.FirebaseInstanceId;
import com.google.firebase.iid.FirebaseInstanceIdService;

public class MyInstanceIDListenerService extends FirebaseInstanceIdService {

    private static final String TAG = MyInstanceIDListenerService.class.getSimpleName();

    @Override
    public void onTokenRefresh() {
        //ここで取得したInstanceIDをサーバー管理者に伝える

        String refreshedToken = FirebaseInstanceId.getInstance().getToken();
        Log.d(TAG, "Refreshed token: " + refreshedToken);
    }
}

Windows

keytool -exportcert -list -v \
-alias androiddebugkey -keystore %USERPROFILE%\.android\debug.keystore