布局

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

    <android.support.design.widget.CoordinatorLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:fitsSystemWindows="true">

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

            <!--记得要设layout_scrollFlags-->
            <android.support.design.widget.CollapsingToolbarLayout
                android:layout_width="match_parent"
                android:layout_height="250dp"
                android:fitsSystemWindows="true"
                app:contentScrim="?attr/colorPrimary"
                app:layout_scrollFlags="scroll|exitUntilCollapsed"
                android:id="@+id/collapse_toolbar">
                <!--这里的高度很关键，决定了收缩后顶部的高度-->
                <!--如果想收缩后还有其他控件就设大一点，否则wrap_content就好了-->
                <!--layout_collapseMode设为pin的话ImageView最后会留在顶部-->
                <ImageView
                    android:layout_width="match_parent"
                    android:layout_height="100dp"
                    android:gravity="top"
                    android:minHeight="?attr/actionBarSize"
                    app:layout_collapseMode="pin"
                    app:titleMarginTop="15dp"
                    android:src="@mipmap/ic_launcher"/>

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

        <!--一定要把layout_behavior设为@string/appbar_scrolling_view_behavior-->
        <android.support.v7.widget.RecyclerView
            android:id="@+id/moive_rv"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_behavior="@string/appbar_scrolling_view_behavior">
        </android.support.v7.widget.RecyclerView>

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