PopupWindow7.0以上的适配

 if (Build.VERSION.SDK_INT < 24){
            // Android 7.0以下
            popupWindow.showAsDropDown(getBaseTopLayout(), 0, 0);
        } else{
            Rect rect = new Rect();
            getBaseTopLayout().getGlobalVisibleRect(rect);
            int h = getBaseTopLayout().getResources().getDisplayMetrics().heightPixels - rect.bottom;
            popupWindow.setHeight(h);
            popupWindow.showAsDropDown(getBaseTopLayout(), 0, 0);
        }