当应用程序未运行时，FCM 显示默认消息而不是自定义消息

Question

问题：我的 FCM 代码针对不同情况显示不同的消息：

案例 1：当应用程序运行时，它显示自定义通知正文

案例 2：当应用程序在后台运行时，它显示自定义通知正文

情况 3：当应用程序未运行时，它显示从 FCM 收到的默认消息而不是自定义消息

代码：

/* The class extends FirebaseMessagingService() */

override fun onMessageReceived(remoteMessage: RemoteMessage) {
        try {
/* Some other codes */            

            val pendingIntent = PendingIntent.getActivity(this, 0, Intent(), PendingIntent.FLAG_ONE_SHOT)
            val builder = NotificationCompat.Builder(this, "" + R.string.notification_channel_id)
                    .setSmallIcon(R.mipmap.ic_launcher_round)
                    .setContentTitle(remoteMessage.notification!!.title)
                    .setContentText(getString(R.string.custom_message_body))
                    .setAutoCancel(true)
                    .setContentIntent(pendingIntent)
            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                val channel = NotificationChannel("" + R.string.notification_channel_id, "Alert channel", NotificationManager.IMPORTANCE_DEFAULT)
                manager.createNotificationChannel(channel)
            }
            manager.notify(0, builder.build())

/* super.onMessageReceived(remoteMessage) was REMOVED to prevent default functions */
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

Answer 1

这是预期的。FCM 对应用程序状态（前台和后台/已终止）有不同的行为。根据您的用例，您应该通过从服务器发送的有效负载来处理此问题。

从服务器发送的 msg 必须以“通知”或“数据”格式从仪表板或服务器端 api 发送。注意：从 firebase dashobard 您只能发送“通知”正文而不是数据。在这种情况下，FCM 将直接显示通知而不会给您的应用程序回调。

服务器端 以下是示例格式：

通知类型格式 注意：Android 系统默认会在通知托盘中显示通知，您不需要显示它。

 { 
    "to": "your_token_id",
     "notification" : {
             "title" : "FCM Notification title!",
             "body" : "FCM Notification subtext!",
             "content_available" : true,
             "priority" : "high"
     }
}

数据格式（用于在应用程序中接收回调，在前台和后台） 注意：您必须自己处理回调和显示通知。

{ 
    "to": "your_token_id",

    "data" : {
         "title" : "FCM Notification Title ",
         "subtext" : "FCM Notification Sub Title",
         "type" : "999",
         "priority" : "high"
    }
}

Android 客户端 要处理在您的 Android 接收器中接收到的有效负载，请在此处查看官方指南

/* The class extends FirebaseMessagingService() */   
 override fun onMessageReceived(remoteMessage: RemoteMessage) {

        Log.d(TAG, "From: ${remoteMessage.from}")

        // Check if message contains a data payload.
        remoteMessage.data.isNotEmpty().let {
            Log.d(TAG, "Message data payload: " + remoteMessage.data)

        if (/* Check if data needs to be processed by long running job */ true) {
            // For long-running tasks (10 seconds or more) use WorkManager.
            scheduleJob()
        } else {
            // Handle message within 10 seconds
            handleNow()
        }
    }

    // Check if message contains a notification payload.
    remoteMessage.notification?.let {
        Log.d(TAG, "Message Notification Body: ${it.body}")
    }

    // 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.
}

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