下面是一个简单的circle_background.xml，用于预材料：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="oval">
            <solid android:color="@color/color_accent_dark" />
        </shape>
    </item>
    <item>
        <shape android:shape="oval">
            <solid android:color="@color/color_accent" />
        </shape>
    </item>
</selector>

您可以在按钮的布局定义中使用属性'android:background=“@drawable/circle_background”

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

    <stroke
        android:width="10dp"
        android:color="@color/white"/>

    <gradient
        android:startColor="@color/red"
        android:centerColor="@color/red"
        android:endColor="@color/red"
        android:angle="270"/>

    <size 
        android:width="250dp" 
        android:height="250dp"/>
</shape>

你可以试试这个-

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="ring"
    android:innerRadiusRatio="700"
    android:thickness="100dp"
    android:useLevel="false">

    <solid android:color="#CCC" />

</shape>

此外，您可以通过调整android：厚度来调整圆的半径。

您可以按如下方式使用VectorDrawable：

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="200dp"
    android:height="200dp"
    android:viewportHeight="64"
    android:viewportWidth="64">

    <path
        android:fillColor="#ff00ff"
        android:pathData="M22,32
        A10,10 0 1,1 42,32
        A10,10 0 1,1 22,32 Z" />
</vector>

上述xml呈现为：

res/drawable/circle_shape.xml

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

        <shape android:shape="oval">
            <solid android:color="#e42828"/>
            <stroke android:color="#3b91d7" android:width="5dp"/>
            <!-- Set the same value for both width and height to get a circular shape -->
            <size android:width="250dp" android:height="250dp"/>
        </shape>
    </item>
</selector>

尝试以下带破折号的代码：

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval">
<size
    android:width="@dimen/_60sdp"
    android:height="@dimen/_60sdp" />

<solid android:color="@color/black" />

<stroke
    android:width="@dimen/_1sdp"
    android:color="@color/white"
    android:dashWidth="@dimen/_1sdp"
    android:dashGap="@dimen/_1sdp" />

尝试不带破折号的代码：

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

<size
    android:width="@dimen/_60sdp"
    android:height="@dimen/_60sdp" />

<solid android:color="@color/black" />

<stroke
    android:width="@dimen/_1sdp"
    android:color="@color/white" />