spinner自定义[转]

转自：https://www.jianshu.com/p/7b03ade29091

spinner_drop_down_shape的代码

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <solid android:color="#FFFFFF"/>
            <corners android:radius="2dip"/>
            <stroke
                    android:width="1dip"
                    android:color="#FFFFFF"/>
        </shape>
    </item>
    <item>
        <bitmap
                android:gravity="end"
                android:src="@drawable/ic_pr_arrow_drop_down"/>
    </item>
</layer-list>