在Android项目中使用FCM(FirebaeCloudMessage)

What

FCM是GCM的升级版本(Google 官方说法)，是一种消息推送框架。

Why

使用FCM进行推送，与GCM相比，功能相同，但是FCM支持从FirebaseConsole发送通知，而GCM不能再控制台发送通知。

How

1.在Firebase中建立想要推送功能的App

2.下载google-services.json文件，并将文件放置在app目录下

说明：如果要在不同buildType或者productFlavors下区分不同的json文件，请建立对应的文件夹，并将json文件cpoy至对应文件夹的根目录下

• 不同的buildType时

// dogfood and release are build types.app/    google-services.json    src/dogfood/google-services.json    src/release/google-services.json    ...

• 不同的productFlavors时

// free and paid are product flavors.app/    google-services.json    src/dogfood/paid/google-services.json    src/release/free/google-services.json    ...

3.加入Firebase需要的包

• 在Project-level的build.gradle中加入：

buildscript {    dependencies {        ...        classpath 'com.google.gms:google-services:3.0.0'        ...    }}

• 在Module-level的build.gradle中加入：

android {  ...}dependencies {    //版本可能更新，请自行修改    ...    compile 'com.google.firebase:firebase-core:10.2.1'    compile 'com.google.firebase:firebase-messaging:10.2.1'    ...}//在最后一行添加apply plugin: 'com.google.gms.google-services'

4.添加FCM相关服务

• 新建MyFirebaseMessagingService，通过继承FirebaseMessagingService实现接受服务

public class MyFirebaseMessagingService extends FirebaseMessagingService{    private static final String TAG = "Fireabse Cloud Message";    /**     * Called when message is received.     *     * @param remoteMessage Object representing the message received from Firebase Cloud Messaging.     */    // [START receive_message]    @Override    public void onMessageReceived(RemoteMessage remoteMessage) {        Log.e("receive", "receive");        // [START_EXCLUDE]        // 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 GCM. 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        // [END_EXCLUDE]        // TODO(developer): Handle FCM messages here.        // Not getting messages here? See why this may be: https://goo.gl/39bRNJ        Log.d(TAG, "From: " + remoteMessage.getFrom());        // Check if message contains a data payload.        if (remoteMessage.getData().size() > 0) {            Log.d(TAG, "Message data payload: " + remoteMessage.getData());            if (/* Check if data needs to be processed by long running job */ true) {                // For long-running tasks (10 seconds or more) use Firebase Job Dispatcher.                scheduleJob();            } else {                // Handle message within 10 seconds                handleNow();            }        }        // Check if message contains a notification payload.        if (remoteMessage.getNotification() != null) {            Log.d(TAG, "Message Notification Body: " + remoteMessage.getNotification().getBody());        }        // Also if you intend on generating your own notifications as a result of a received FCM        // message, here is where that should be initiated. See sendNotification method below.        sendNotification(remoteMessage.getNotification().getBody());    }    // [END receive_message]    /**     * Schedule a job using FirebaseJobDispatcher.     */    private void scheduleJob() {        /*        // [START dispatch_job]        FirebaseJobDispatcher dispatcher = new FirebaseJobDispatcher(new GooglePlayDriver(this));        Job myJob = dispatcher.newJobBuilder()                .setService(MyJobService.class)                .setTag("my-job-tag")                .build();        dispatcher.schedule(myJob);        // [END dispatch_job]        */    }    /**     * Handle time allotted to BroadcastReceivers.     */    private void handleNow() {        Log.d(TAG, "Short lived task is done.");    }    /**     * Create and show a simple notification containing the received FCM message.     *     * @param messageBody FCM message body received.     */    private void sendNotification(String messageBody) {        Intent intent = new Intent(this, MainActivity.class);        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,                PendingIntent.FLAG_ONE_SHOT);        Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)                .setSmallIcon(R.mipmap.ic_launcher)                .setContentTitle("FCM Message")                .setContentText(messageBody)                .setAutoCancel(true)                .setSound(defaultSoundUri)                .setContentIntent(pendingIntent);        NotificationManager notificationManager =                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);        notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());    }}

• 新建MyFirebaseInstanceIDService，通过继承FirebaseInstanceIDService实现设备Token的获取。

public class MyFirebaseInstanceIDService extends FirebaseInstanceIdService{    private static final String TAG = "FCM Token";    @Override    public void onTokenRefresh() {        // Get updated InstanceID token.        String refreshedToken = FirebaseInstanceId.getInstance().getToken();        Log.d(TAG, "Refreshed token: " + refreshedToken);        // If you want to send messages to this application instance or        // manage this apps subscriptions on the server side, send the        // Instance ID token to your app server.        sendRegistrationToServer(refreshedToken);    }    private void sendRegistrationToServer(String token){        //// TODO: upload your token    }}

5.在manifest文件中声明服务

<service    android:name=".MyFirebaseMessagingService">    <intent-filter>        <action android:name="com.google.firebase.MESSAGING_EVENT"/>    </intent-filter></service><service    android:name=".MyFirebaseInstanceIDService">    <intent-filter>        <action android:name="com.google.firebase.INSTANCE_ID_EVENT"/>    </intent-filter></service>

6.在manifest文件中设置当App后天运行时接收Notification样式

<!-- Set custom default icon. This is used when no icon is set for incoming notification messages. See README(https://goo.gl/l4GJaQ) for more. -->    <meta-data        android:name="com.google.firebase.messaging.default_notification_icon"        android:resource="@drawable/study" />    <!-- Set color used with incoming notification messages. This is used when no color is set for the incoming         notification message. See README(https://goo.gl/6BKBk7) for more. -->    <meta-data        android:name="com.google.firebase.messaging.default_notification_color"        android:resource="@color/colorAccent" />

7.使用注意问题：

7.1 程序前台运行

程序前台运行时，接受到通知会走MyFirebaseMessagingService的onMessageReceived方法，此时，可以自定义处理。

7.2 程序后台运行

程序后台运行时接收到通知，不会走MyFirebaseMessagingService的onMessageReceived方法，而是显示在系统托盘中，此时点击通知，会打开App中的默认启动Activity，并将数据放在Intent的extras中传送。

• 如何处理数据？
  可以在创建Activity时获取数据，然后进行处理
• 当程序后台时，接收到了多个Notification时，如何处理？
  当收到多个通知时，如果Activity不是SingleTop、SingleTask或SingleInstance，每点击一次通知，就会创建一个Activity，可以在Intent中获取数据。如果是另外三种方式，可以通过newIntent方法回调获取intent中的数据。