您正在发送 data -仅 PHP中的有效负载:

You are sending a data-only payload in your PHP:

public function send($to, $message) {
    $fields = array(
        'to' => $to,
        //'data' => $message,
        'data' => array("message" => $message));

    return $this->sendPushNotification($fields);
}

_{您的其他方法也发送相同的内容.}

如果要使用仅notification的有效负载，则可以像这样简单地构造它:

If you're going to use a notification-only payload, you could simply structure it like so:

public function send($to, $message) {
    $fields = array(
        'to' => $to,
        'notification' => array("title" => $title,
            "body" => $body));

    return $this->sendPushNotification($fields);
}

与从Firebase控制台发送消息的区别在于，来自控制台的消息被视为 notification 消息.

The difference from sending a message from the Firebase Console is that messages from the console are considered as notification messages.

在Android中，每种消息类型的处理方式都不同(请参见处理消息).

In Android, each message type is handled differently (see Handling Messages).

一些有用的帖子:

• FCM通知问题
• 我们能否仅从Firebase通知控制台推送数据消息

• Issue with FCM notification
• Can we push only data message from Firebase Notification console