用于前台服务的Android 8通知通道

Question

我想知道我的通知创建源的以下修改是否符合Android 8。 之前：

Notification.Builder builder = new Notification.Builder(this);
// ... (some code omitted)
myNotification = builder.build();
// ... (some code omitted)
startForeground(MY_NOTIFICATION_ID, myNotification);

后：

Notification.Builder builder;
if ( Build.VERSION.SDK_INT < 26 ) {
    builder = new Notification.Builder(this);
} else {
    final String ChannelId = "mypackage.NotificationChannelID";
    final CharSequence ChannelName = "My Notification";
    NotificationChannel channel = new NotificationChannel(ChannelId, ChannelName, NotificationManager.IMPORTANCE_LOW);
    ((NotificationManager)this.getSystemService(Context.NOTIFICATION_SERVICE)).
        createNotificationChannel(channel);
    builder = new Notification.Builder(this, ChannelId);
}
// ... (some code omitted)
myNotification = builder.build();
// ... (some code omitted)
startForeground(MY_NOTIFICATION_ID, myNotification);

特别是，至少还有两个问题：

（1）我想知道是否以及在哪里添加void deleteNotificationChannel(String channelId)以不产生任何内存泄漏？

（2）我应该添加builder.setCategory(Notification.CATEGORY_SERVICE)，如果是，为什么？