<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <!-- 填充的颜色 -->
    <solid android:color="#90000000" />
    <!-- 设置按钮的四个角为弧形 -->
    <corners android:radius="3dp"/>

</shape>