<?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="#000000" />
</shape>
</item>
<item android:bottom="1dp"> <!--设置只有底部有边框-->
<shape>
<solid android:color="#ffffff" />
</shape>
</item>
</layer-list>