Android7.0以上Popupwindow显示在控件下方问题

@Override
public void showAsDropDown(View anchor) {
    if (Build.VERSION.SDK_INT >= 24) {
        Rect rect = new Rect();
        anchor.getGlobalVisibleRect(rect);
        int h = anchor.getResources().getDisplayMetrics().heightPixels - rect.bottom;
        setHeight(h);
    }
    super.showAsDropDown(anchor);
}