首先在style裡面加入

<style name="ThemeSplash" parent="Theme.AppCompat.Light.NoActionBar">
<!--<item name="android:background">@mipmap/ic_launcher</item>-->
<item name="android:windowBackground">@mipmap/aaa</item>
    <item name="android:windowNoTitle">true</item>
 
    <item name="android:windowFullscreen">true</item>
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
</style>

<activity
android:name=".Splash"
android
 
:theme="@style/ThemeSplash">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

try{
    Thread.sleep(2000);
} catch 
 
(InterruptedException e) {
    e.printStackTrace();
}
Intent it = new Intent(this,MainActivity.class);
startActivity(it);
finish();

完成。。。