• 代码如下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <RadioGroup
        android:id="@+id/rd_group"
        android:layout_marginTop="30dp"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
        <RadioButton
            android:id="@+id/left"
            android:layout_width="100dp"
            android:layout_height="wrap_content"
            android:background="@drawable/button_left"
            android:button="@null"
            android:checked="true"
            android:clickable="true"
            android:gravity="center"
            android:text="左"
            android:textSize="15sp" />

        <RadioButton
            android:id="@+id/center"
            android:text="中"
            android:gravity="center"
            android:textSize="15sp"
            android:layout_width="100dp"
            android:layout_height="wrap_content"
            android:button="@null"
            android:clickable="true"
            android:background="@drawable/button_center"
            />
        <RadioButton
            android:id="@+id/right"
            android:text="右"
            android:gravity="center"
            android:textSize="15sp"
            android:layout_width="100dp"
            android:layout_height="wrap_content"
            android:button="@null"
            android:clickable="true"
            android:background="@drawable/button_right"
            />
    </RadioGroup>
</LinearLayout>

• button_left

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

    <item android:drawable="@drawable/btn_left_press" android:state_checked="true"/>
    <item android:drawable="@drawable/btn_left_nol"/>

</selector>

• btn_left_press

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="#7766E7" />
    <corners android:topLeftRadius="16dp"
        android:topRightRadius="0dp"
        android:bottomLeftRadius="16dp"
        android:bottomRightRadius="0dp"/>
</shape>

• btn_left_nol

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

    <corners android:topLeftRadius="16dp"
        android:topRightRadius="0dp"
        android:bottomLeftRadius="16dp"
        android:bottomRightRadius="0dp"/>
    <stroke android:width="1dp" android:color="#7766E7" />
    <solid android:color="#F5F6FA" />

</shape>

• button_center

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

    <item android:drawable="@drawable/btn_center_press" android:state_checked="true"/>
    <item android:drawable="@drawable/btn_center_nol"/>

</selector>

• btn_center_press

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="#7766E7" />
</shape>

• btn_center_nol

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

    <stroke android:width="1dp" android:color="#7766E7" />
    <solid android:color="#F5F6FA" />

</shape>-->
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <solid android:color="#7766E7" />  //边框颜色
        </shape>
    </item>
<!--    想保留哪一边就设置哪一边边框，列如只有下边框：bottom="0.7dp"，相应的有上top="",left="",right=""    -->
    <item android:bottom="1dp" android:top="1dp">
        <shape>
            <solid android:color="#F5F6FA" />  //整个框背景颜色
        </shape>
    </item>
</layer-list>

• button_right

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

    <item android:drawable="@drawable/btn_right_press" android:state_checked="true"/>
    <item android:drawable="@drawable/btn_right_nol"/>

</selector>

• btn_right_press

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="@color/main_color" />
    <corners android:topLeftRadius="0dp"
        android:topRightRadius="16dp"
        android:bottomLeftRadius="0dp"
        android:bottomRightRadius="16dp"/>
</shape>

• btn_right_nol

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

    <corners android:topLeftRadius="0dp"
        android:topRightRadius="16dp"
        android:bottomLeftRadius="0dp"
        android:bottomRightRadius="16dp"/>
    <stroke android:width="1dp" android:color="#7766E7" />
    <solid android:color="#F5F6FA" />

</shape>

• 左、右、中的点击事件处理

rdGroup=findViewById(R.id.rd_group);
rdGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int i) {
                switch (radioGroup.getCheckedRadioButtonId()){
                    case R.id.left:
                        //点击左面的处理
                        break;
                    case R.id.center:
                        //点击右面的处理
                        break;
                    case R.id.right:
                        //点击中间的处理
                        break;
                }
            }
        });