AppCompatActivity set transparent theme

I can't do it after a lot of Baidu. I don't know how everyone got it. Let me make a remark first:

<style name="protect_transparent" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowBackground">@color/transparent</item>
    <item name="android:windowIsTranslucent">true</item>
</style>