CollapsingToolbarLayout 在片段中时不能有透明的状态栏

Question

我有一个简单的 CollapsingToolbarLayout。一切正常，并且在滚动页面之前状态栏是透明的，正如预期的那样（透明）：

当我将 CoordinatorLayout 标记及其包含 CollapsingToolbarLayout 的内容从 activity_main.xml 传输到片段时出现问题，状态栏不再透明！为什么？！我没有更改任何部分代码，只是复制了一段代码并将其粘贴到此处的片段中（不再透明）：

代码如下：

MainActivity.java

public class MainActivity extends AppCompatActivity implements TestFragment.OnFragmentInteractionListener {    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

            if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.main_fragment, new TestFragment())
                    .commit();
        }

    }

}

activity_main.xml

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".MainActivity">

    <FrameLayout
        android:id="@+id/main_fragment"
        android:fitsSystemWindows="true"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </FrameLayout>

</android.support.v4.widget.DrawerLayout>

fragment_test.xml

<android.support.design.widget.CoordinatorLayout     xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".TestFragment">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="256dp"
        android:fitsSystemWindows="true"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            app:contentScrim="@color/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            >

            <ImageView
                app:layout_collapseMode="pin"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="true"
                android:scaleType="centerCrop"
                android:src="@drawable/toolbar_bg" />

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                app:layout_collapseMode="pin"
                app:layout_scrollFlags="scroll|enterAlways"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:popupTheme="@style/AppTheme.PopupOverlay"
                android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"/>

        </android.support.design.widget.CollapsingToolbarLayout>

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="fill_vertical"
        app:behavior_overlapTop="32dp"
        android:background="@color/main_bg">


    </android.support.v4.widget.NestedScrollView>


    <android.support.design.widget.FloatingActionButton
        app:fabSize="normal"
        app:layout_anchor="@id/appbar"
        app:layout_anchorGravity="bottom|right"
        app:srcCompat="@drawable/ic_add_black_24dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:onClick="FABTouched"
        android:tint="@color/main_bg"
        />

</android.support.design.widget.CoordinatorLayout>

styles.xml

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="android:statusBarColor">@android:color/transparent</item>
</style>
<style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />
<style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

Answer 1

将 FrameLayout 更改为 CoordinatorLayout。