用shape进行画线
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line">
<stroke android:width="1dp" android:color="#000000"
android:dashWidth="1dp" android:dashGap="0dp" />
<size android:height="2dp" />
</shape>