<Switch
  android:id="@+id/switch_btn"
  android:layout_width="wrap_content"
  android:layout_height="24dp"
  android:layout_marginRight="10dip"
  android:checked="true"
  android:splitTrack="false"
  android:switchMinWidth="50dp"
  android:thumb="@drawable/ko_switch_thumb_white"
  android:track="@drawable/ko_switch_track_primary"
  android:typeface="serif" />

ko_switch_thumb_white和ko_switch_track_primary文件定义Switch的样式。

ko_switch_thumb_white.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/ko_switch_thumb_on" android:state_checked="true" />
    <item android:drawable="@drawable/ko_switch_thumb_off" android:state_checked="false" />
</selector>

ko_switch_track_primary.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/ko_switch_track_on" android:state_checked="true" />
    <item android:drawable="@drawable/ko_switch_track_off" android:state_checked="false" />
</selector>

ko_switch_thumb_on.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="@color/ko_white" />
    <size
        android:width="24dp"
        android:height="24dp" />
    <stroke
        android:width="5dp"
        android:color="#00000000" />
</shape>

ko_switch_thumb_off.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="@color/ko_white" />
    <size
        android:width="24dp"
        android:height="24dp" />
    <stroke
        android:width="5dp"
        android:color="#00000000" />
</shape>

ko_switch_track_on.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="@color/ko_color_primary" />
    <stroke
        android:width="0dp"
        android:color="#00000000" />
    <corners android:radius="12dp" />
</shape>

ko_switch_track_off.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="#E3E3E3" />
    <stroke
        android:width="0dp"
        android:color="#00000000" />
    <corners android:radius="12dp" />
</shape>