Firebase Cloud Message学习

使用graddle和dependency
// Firebase dependency
compile ‘com.google.firebase:firebase-messaging:10.0.1’

apply plugin: ‘com.google.gms.google-services’
首先要注册Firebase的google账号，在使用FCM的过程中，要知道APP的Firebase token，
String token = FirebaseInstanceId.getInstance().getToken();
String msg = getString(R.string.message_token_format, token);

本项目使用的FCM两种功能：
1、 server对一传播，用google的Firebase发验证信息是notification msg
2、server对多传播，使用FirebaseMessaging.getInstance().subscribeToTopic(key);
能保持对同一个topic subscribe的app进行广播

extend FirebaseMessagingService
override onMessageReceived(RemoteMessage remoteMessage)
通过remoteMessage.getData()获取FCM中的数据

public void onMessageReceived(RemoteMessage remoteMessage) {
     
        // There are two types of messages data messages and notification messages. Data messages
        // are handled
        // here in onMessageReceived whether the app is in the foreground or background. Data
        // messages are the type
        // traditionally used with FCM. Notification messages are only received here in
        // onMessageReceived when the app
        // is in the foreground. When the app is in the background an automatically generated
        // notification is displayed.
        // When the user taps on the notification they are returned to the app. Messages
        // containing both notification
        // and data payloads are treated as notification messages. The Firebase console always
        // sends notification
        // messages. For more see: https://firebase.google.com/docs/cloud-messaging/concept-options\

        // The Squawk server always sends just *data* messages, meaning that onMessageReceived when
        // the app is both in the foreground AND the background

        Log.d(LOG_TAG, "From: " + remoteMessage.getFrom());

        // Check if message contains a data payload.

        Map<String, String> data = remoteMessage.getData();

        if (data.size() > 0) {
     
            Log.d(LOG_TAG, "Message data payload: " + data);

            // Send a notification that you got a new message
            sendNotification(data);
            insertSquawk(data);

        }
    }



public void onMessageReceived(RemoteMessage remoteMessage) {
     
        // There are two types of messages data messages and notification messages. Data messages
        // are handled
        // here in onMessageReceived whether the app is in the foreground or background. Data
        // messages are the type
        // traditionally used with FCM. Notification messages are only received here in
        // onMessageReceived when the app
        // is in the foreground. When the app is in the background an automatically generated
        // notification is displayed.
        // When the user taps on the notification they are returned to the app. Messages
        // containing both notification
        // and data payloads are treated as notification messages. The Firebase console always
        // sends notification
        // messages. For more see: https://firebase.google.com/docs/cloud-messaging/concept-options\

        // The Squawk server always sends just *data* messages, meaning that onMessageReceived when
        // the app is both in the foreground AND the background

        Log.d(LOG_TAG, "From: " + remoteMessage.getFrom());

        // Check if message contains a data payload.

        Map<String, String> data = remoteMessage.getData();

        if (data.size() > 0) {
     
            Log.d(LOG_TAG, "Message data payload: " + data);

            // Send a notification that you got a new message
            sendNotification(data);
            insertSquawk(data);

        }
    }
/**
     * Inserts a single squawk into the database;
     *
     * @param data Map which has the message data in it
     */
    private void insertSquawk(final Map<String, String> data) {
     

        // Database operations should not be done on the main thread
        AsyncTask<Void, Void, Void> insertSquawkTask = new AsyncTask<Void, Void, Void>() {
     

            @Override
            protected Void doInBackground(Void... voids) {
     
                ContentValues newMessage = new ContentValues();
                newMessage.put(SquawkContract.COLUMN_AUTHOR, data.get(JSON_KEY_AUTHOR));
                newMessage.put(SquawkContract.COLUMN_MESSAGE, data.get(JSON_KEY_MESSAGE).trim());
                newMessage.put(SquawkContract.COLUMN_DATE, data.get(JSON_KEY_DATE));
                newMessage.put(SquawkContract.COLUMN_AUTHOR_KEY, data.get(JSON_KEY_AUTHOR_KEY));
                getContentResolver().insert(SquawkProvider.SquawkMessages.CONTENT_URI, newMessage);
                return null;
            }
        };

        insertSquawkTask.execute();
    }


    /**
     * Create and show a simple notification containing the received FCM message
     *
     * @param data Map which has the message data in it
     */
    private void sendNotification(Map<String, String> data) {
     
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        // Create the pending intent to launch the activity
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
                PendingIntent.FLAG_ONE_SHOT);

        String author = data.get(JSON_KEY_AUTHOR);
        String message = data.get(JSON_KEY_MESSAGE);

        // If the message is longer than the max number of characters we want in our
        // notification, truncate it and add the unicode character for ellipsis
        if (message.length() > NOTIFICATION_MAX_CHARACTERS) {
     
            message = message.substring(0, NOTIFICATION_MAX_CHARACTERS) + "\u2026";
        }

        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setSmallIcon(R.drawable.ic_duck)
                .setContentTitle(String.format(getString(R.string.notification_message), author))
                .setContentText(message)
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

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

        notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());
    }