基于以下情况调用的onmessagerecreceived (RemoteMessage RemoteMessage)方法。

FCM响应带有通知和数据块:

{
  
"to": "device token list",
  "notification": {
    "body": "Body of Your Notification",
    "title": "Title of Your Notification"
  },
  "data": {
    "body": "Body of Your Notification in Data",
    "title": "Title of Your Notification in Title",
    "key_1": "Value for key_1",
    "image_url": "www.abc.com/xyz.jpeg",
    "key_2": "Value for key_2"
  }
}

应用程序在前台:

onmessagerreceived (RemoteMessage RemoteMessage)调用，在通知栏中显示LargeIcon和BigPicture。我们可以从通知和数据块中读取内容

后台应用:

onmessagerreceived (RemoteMessage RemoteMessage)未被调用，系统托盘将接收消息并从通知块中读取正文和标题，并在通知栏中显示默认消息和标题。

只有数据块的FCM响应:

在本例中，从json中删除通知块

{
  
"to": "device token list",
  "data": {
    "body": "Body of Your Notification in Data",
    "title": "Title of Your Notification in Title",
    "key_1": "Value for key_1",
    "image_url": "www.abc.com/xyz.jpeg",
    "key_2": "Value for key_2"
  }
}

调用onmessagerreceived()的解决方案

应用程序在前台:

onmessagerreceived (RemoteMessage RemoteMessage)调用，在通知栏中显示LargeIcon和BigPicture。我们可以从通知和数据块中读取内容

后台应用:

onmessagerreceived (RemoteMessage RemoteMessage)调用，系统托盘将不会收到消息，因为通知键不在响应中。在通知栏中显示LargeIcon和BigPicture

Code

 private void sendNotification(Bitmap bitmap,  String title, String 
    message, PendingIntent resultPendingIntent) {

    NotificationCompat.BigPictureStyle style = new NotificationCompat.BigPictureStyle();
    style.bigPicture(bitmap);

    Uri defaultSound = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);

    NotificationManager notificationManager = (NotificationManager) mContext.getSystemService(Context.NOTIFICATION_SERVICE);
    String NOTIFICATION_CHANNEL_ID = mContext.getString(R.string.default_notification_channel_id);

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "channel_name", NotificationManager.IMPORTANCE_HIGH);

        notificationManager.createNotificationChannel(notificationChannel);
    }
    Bitmap iconLarge = BitmapFactory.decodeResource(mContext.getResources(),
            R.drawable.mdmlogo);
    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(mContext, NOTIFICATION_CHANNEL_ID)
            .setSmallIcon(R.drawable.mdmlogo)
            .setContentTitle(title)
            .setAutoCancel(true)
            .setSound(defaultSound)
            .setContentText(message)
            .setContentIntent(resultPendingIntent)
            .setStyle(style)
            .setLargeIcon(iconLarge)
            .setWhen(System.currentTimeMillis())
            .setPriority(Notification.PRIORITY_MAX)
            .setChannelId(NOTIFICATION_CHANNEL_ID);


    notificationManager.notify(1, notificationBuilder.build());


}

参考链接:

https://firebase.google.com/docs/cloud-messaging/android/receive

我也有同样的问题。使用“数据消息”而不是“通知”更容易。数据消息总是加载类onmessagerreceived。

在该类中，您可以使用notificationbuilder创建自己的通知。

例子:

 @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        sendNotification(remoteMessage.getData().get("title"),remoteMessage.getData().get("body"));
    }

    private void sendNotification(String messageTitle,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_UPDATE_CURRENT);

        long[] pattern = {500,500,500,500,500};

        Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);

        NotificationCompat.Builder notificationBuilder = (NotificationCompat.Builder) new NotificationCompat.Builder(this)
                .setSmallIcon(R.drawable.ic_stat_name)
                .setContentTitle(messageTitle)
                .setContentText(messageBody)
                .setAutoCancel(true)
                .setVibrate(pattern)
                .setLights(Color.BLUE,1,1)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());
    }

值得强调的一点是，你必须使用数据消息-数据键-让onmessagerecreceived处理程序被调用，即使应用程序是在后台。你不应该在你的有效负载中有任何其他通知消息键，否则如果应用程序在后台，处理程序将不会被触发。

这里提到了(但在FCM文档中没有特别强调):

https://firebase.google.com/docs/cloud-messaging/concept-options#notifications_and_data_messages

使用您的应用服务器和FCM服务器API:只设置数据键。可以 要么可折叠，要么不可折叠。

这是预期的工作，通知消息只有当你的应用程序在前台时才被传递到你的onmessagerreceived回调。如果你的应用程序在后台或关闭，那么通知中心会显示一条通知消息，来自该消息的任何数据都会传递给意图，而用户点击通知的结果就是启动该消息。

您可以在JSON中指定click_action，以指示当用户点击通知时应该启动的意图。如果没有指定click_action，则使用主活动。

当意图启动时，你可以使用

getIntent().getExtras();

检索包含随通知消息一起发送的任何数据的Set。

有关通知消息的更多信息，请参阅文档。

在MainActivity的onCreate方法中调用这个:

if (getIntent().getExtras() != null) {
           // Call your NotificationActivity here..
            Intent intent = new Intent(MainActivity.this, NotificationActivity.class);
            startActivity(intent);
        }

根据t3h Exi的解决方案，我想在这里发布干净的代码。只要把它放入MyFirebaseMessagingService，如果应用程序处于后台模式，一切都可以正常工作。您至少需要编译com.google.firebase:firebase-messaging:10.2.1

 @Override
public void handleIntent(Intent intent)
{
    try
    {
        if (intent.getExtras() != null)
        {
            RemoteMessage.Builder builder = new RemoteMessage.Builder("MyFirebaseMessagingService");

            for (String key : intent.getExtras().keySet())
            {
                builder.addData(key, intent.getExtras().get(key).toString());
            }



           onMessageReceived(builder.build());
        }
        else
        {
            super.handleIntent(intent);
        }
    }
    catch (Exception e)
    {
        super.handleIntent(intent);
    }
}