我认为我已经找到答案了.只需从底部工作表中删除 android:fitsSystemWindows ="true" ，即LinearLayout.以防万一我将xml代码放在下面.

I think I have got the answer. Just need to remove the android:fitsSystemWindows="true" from bottom_sheet i.e the LinearLayout. Just in case I am putting the xml code below.

<?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"
    android:fitsSystemWindows="true"
    android:id="@+id/coordinatorLayout"
    tools:context=".MainActivity">

    <include layout="@layout/content_main" />


    <LinearLayout android:layout_width="match_parent"
        android:layout_height="wrap_content"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:orientation="horizontal"
        app:behavior_hideable="true"
        app:behavior_peekHeight="0dp"
        android:id="@+id/bottom_sheet"
        android:background="@android:color/holo_orange_light"
        app:layout_behavior="@string/bottom_sheet_behavior" 
        xmlns:android="http://schemas.android.com/apk/res/android">

        <ImageView
            android:layout_weight="1"
            android:layout_margin="@dimen/five"
            android:padding="@dimen/ten"
            android:src="@drawable/ic_photo_camera"
            android:layout_width="@dimen/fifty"
            android:layout_height="@dimen/fifty" />

        <ImageView
            android:layout_weight="1"
            android:layout_margin="@dimen/five"
            android:padding="@dimen/ten"
            android:src="@drawable/ic_image_gallery"
            android:layout_width="@dimen/fifty"
            android:layout_height="@dimen/fifty" />

        <ImageView
            android:layout_weight="1"
            android:layout_margin="@dimen/five"
            android:padding="@dimen/ten"
            android:src="@drawable/ic_video_camera"
            android:layout_width="@dimen/fifty"
            android:layout_height="@dimen/fifty" />

        <ImageView
            android:layout_weight="1"
            android:layout_margin="@dimen/five"
            android:padding="@dimen/ten"
            android:src="@drawable/ic_video_camera"
            android:layout_width="@dimen/fifty"
            android:layout_height="@dimen/fifty" />


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

仅供我使用，我使用了其他可绘制对象，您需要将其更改回原始对象.

Just for my use, I have used different drawable you need to change it back to the original one.

希望有帮助！