在style.xml中定义：
<style name="FullScreenTheme" parent="Theme.AppCompat.Light.NoActionBar">
<!-- Customize your theme here. -->
<item name="android:windowFullscreen">true</item>
</style>
使用：
<activity android:name=".ui.SplashActivity" android:screenOrientation="portrait"
android:theme="@style/FullScreenTheme"
