Android 边框，只有底部边框

<?xml version="1.0" encoding="UTF-8"?><layer-list xmlns:android="http://schemas.android.com/apk/res/android" >    <!-- 边框颜色值 -->    <item>        <shape>            <solid android:color="@color/common_background" />        </shape>    </item>    <!-- 主体背景颜色值 -->    <item        android:top="0dp"        android:left="0dp"        android:right="0dp"        android:bottom="2dp">        <shape>            <solid android:color="@color/white" />        </shape>    </item></layer-list>