在onMessageReceived中显示默认通知

@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
    // 获取推送消息的标题和内容
    String title = remoteMessage.getNotification().getTitle();
    String content = remoteMessage.getNotification().getBody();

    // 构建默认通知
    NotificationCompat.Builder builder = new NotificationCompat.Builder(this)
            .setSmallIcon(R.drawable.notification_icon)
            .setContentTitle(title)
            .setContentText(content)
            .setAutoCancel(true);

    // 显示通知
    NotificationManager notificationManager =
            (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    notificationManager.notify(0, builder.build());
}