Flutter闪屏不适用于launch_background.xml

我似乎不能显示我自己的闪屏，每次我启动应用程序时，都会显示默认的空白闪屏，即使我已经在launch_background.xml中设置了所有的东西，在res中设置了其他文件.我还在drawable和mipmap中设置了所有相关图标.

在后台启动.xml:

<!-- Modify this file to customize your launch splash screen -->
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <color android:color="@color/splash" />
    </item>

    <!-- You can insert your own image assets here -->
    <item>
        <bitmap
            android:gravity="center"
            android:src="@drawable/splash_icon" />
    </item>
</layer-list>

style es.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
        <!-- Show a splash screen on the activity. Automatically removed when
             Flutter draws its first frame -->
        <item name="android:windowBackground">@drawable/launch_background</item>
    </style>
    <!-- Theme applied to the Android Window as soon as the process has started.
         This theme determines the color of the Android Window while your
         Flutter UI initializes, as well as behind your Flutter UI while its
         running.
         
         This Theme is only used starting with V2 of Flutter's Android embedding. -->
    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
        <item name="android:windowBackground">?android:colorBackground</item>
    </style>
</resources>

colored颜色 .xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="ic_launcher_background">#191919</color>
    <color name="splash">#191919</color>
</resources>

AndroidManifest.xml中的<activity>标签:

<activity
            android:name=".MainActivity"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/LaunchTheme"
              />
            <!-- Displays an Android View that continues showing the launch screen
                 Drawable until Flutter paints its first frame, then this splash
                 screen fades out. A splash screen is useful to avoid any visual
                 gap between the end of Android's launch screen and the painting of
                 Flutter's first frame. -->
            <meta-data
              android:name="io.flutter.embedding.android.SplashScreenDrawable"
              android:resource="@drawable/launch_background"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>

闪屏应该显示一个图像和不同的背景 colored颜色 ，但是它只显示默认的空白白屏.我不会为此使用自定义闪屏.我只想至少改变一下 colored颜色 ，但即使这样也不行.