<?xml version="1.0" encoding="utf-8"?><!-- 中心背景 -->
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <!-- 实心 -->
    <solid android:color="#ffffff" />
    <corners
        android:topLeftRadius="20dp"
        android:topRightRadius="20dp" />
</shape>