drawableRightset 和 CompoundDrawables
android:drawableRight="@drawable/check_down"
在代码中的用法是：
Drawable drawable = getResources().getDrawable(R.drawable.spinner_checked);
drawable.setBounds(0, 0, drawable.getMinimumWidth(), drawable.getMinimumHeight()); //设置边界
titleTv.setCompoundDrawables(null, null, drawable, null); //画在右边