问CoordinatorLayout中的容器，其CollapsingToolbarLayout大于系统窗口

EN

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/parent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorBackground"
        android:fitsSystemWindows="true">

        <android.support.design.widget.AppBarLayout
            android:id="@+id/app_bar"
            android:layout_width="match_parent"
            android:layout_height="160dp"
            android:background="@color/colorBackground"
            android:fitsSystemWindows="true"
            android:theme="@style/AppTheme.AppBarOverlay">

            <android.support.design.widget.CollapsingToolbarLayout
                android:id="@+id/toolbar_layout"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="true"
                app:contentScrim="?attr/colorPrimary"
                app:expandedTitleMarginStart="64dp"
                app:layout_scrollFlags="scroll|exitUntilCollapsed"
                app:toolbarId="@+id/toolbar">

                <android.support.v7.widget.Toolbar
                    android:id="@+id/toolbar"
                    android:layout_width="match_parent"
                    android:layout_height="?attr/actionBarSize"
                    app:layout_collapseMode="pin"
                    app:navigationIcon="@drawable/ic_arrow_back"
                    app:popupTheme="@style/AppTheme.PopupOverlay" />

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

        <FrameLayout
            android:id="@+id/container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />

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

public class MainActivity extends AppCompatActivity {
    ActivityAddPlanBinding binding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_add_plan);
        setSupportActionBar(binding.toolbar);
        initContainerHeights();
    }

    int appBarHeight;
    int screenHeight;

    private void initContainerHeights() {
        appBarHeight = binding.appBar.getLayoutParams().height;
        screenHeight = screenHeight();
        binding.appBar.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
            @Override
            public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
                binding.container.requestLayout();
                binding.container.getLayoutParams().height = screenHeight - (appBarHeight + verticalOffset);
            }
        });
    }

    private int screenHeight() {
        DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        return displayMetrics.heightPixels - statusBarHeight();
    }

    public int statusBarHeight() {
        final Resources resources = getResources();
        final int resourceId = resources.getIdentifier("status_bar_height", "dimen", "android");
        if (resourceId > 0) {
            return resources.getDimensionPixelSize(resourceId);
        } else {
            return (int) Math.ceil((Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? 24 : 25) * resources.getDisplayMetrics().density);
        }
    }
}