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

    <item android:state_pressed="false">
        <shape android:shape="oval">
            <solid android:color="#64BFEB" />
        </shape>
    </item>

    <item android:state_pressed="true">
        <shape android:shape="oval">
            <!-- 点击按钮时候改变背景色50% -->
            <solid android:color="#8064BFEB" />
        </shape>
    </item>
</selector>