给activity设置<item name="android:windowIsTranslucent">true</item>的style
<activity
android:name=".activity.WelcomeActivity"
android:screenOrientation="portrait"
android:theme="@style/AppTheme.NoActionBar.FullScreen.Translucent">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<style name="AppTheme.FullScreen.Translucent">
<item name="android:windowIsTranslucent">true</item>
</style>
