android5.x以上 状态栏透明的问题

<item name="android:statusBarColor">@android:color/transparent</item>

getWindow().getDecorView().setSystemUiVisibility(
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.chuangyuan.qdocument.activity.AboutActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">
            <FrameLayout    //外面套上framelayout并设置
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:fitsSystemWindows="true">
            <ImageView
                android:layout_width="match_parent"
                android:layout_height="230dp"
                android:src="@drawable/head"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax"
                />

            </FrameLayout>

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                android:background="@android:color/transparent"
               android:layout_marginTop="24dp"    //此时需要给toolbar设置一个状态栏高度的  margin值，否则，会使toolbar中的文字显示不全。
                />
        </android.support.design.widget.CollapsingToolbarLayout>


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

    <android.support.v4.widget.NestedScrollView
        android:id="@+id/nested"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            >

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="a。。。代表很多字" />

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


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