我们先来看看效果

继承RecyclerView.OnScrollListener重写onScrolled方法，同时定义两个抽象方法供我们处理隐藏和显示事件

public abstract class HidingScrollListener extends RecyclerView.OnScrollListener {
    private static final int HIDE_THRESHOLD = 20;
    private int scrolledDistance = 0;
    private boolean controlsVisible = true;


    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        if (scrolledDistance > HIDE_THRESHOLD && controlsVisible) {
            onHide();
            controlsVisible = false;
            scrolledDistance = 0;
        }
        else if (scrolledDistance < -HIDE_THRESHOLD && !controlsVisible) {
            onShow();
            controlsVisible = true;
            scrolledDistance = 0;
        }
        if ((controlsVisible && dy > 0) || (!controlsVisible && dy < 0)) {
            scrolledDistance += dy;
        }

    }


    public abstract void onHide();

    public abstract void onShow();
}

事件的处理

recyclerView.addOnScrollListener(new HidingScrollListener() {

            @Override
            public void onHide() {
                Resources resources = MainActivity.this.getResources();
                DisplayMetrics dm = resources.getDisplayMetrics();
                float density = dm.density;
                int width = dm.widthPixels;
                int height = dm.heightPixels;
                fab.animate()
                        .translationY(height - fab.getHeight())
                        .setInterpolator(new AccelerateInterpolator(2))
                        .start();
                buttom.animate()
                        .translationY(height - buttom.getHeight())
                        .setInterpolator(new AccelerateInterpolator(2))
                        .setDuration(800)
                        .start();
                top.animate()
                        .translationY(-height)
                        .setDuration(800)
                        .setInterpolator(new AccelerateInterpolator(2))
                        .start();
            }

            @Override
            public void onShow() {
                fab.animate().translationY(0).setInterpolator(new DecelerateInterpolator(2)).start();
                buttom.animate().translationY(0).setInterpolator(new DecelerateInterpolator(2)).setDuration(800).start();
                top.animate().translationY(0).setInterpolator(new DecelerateInterpolator(2)).setDuration(800).start();
            }
});

布局文件

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


    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:clipToPadding="false"
        android:paddingTop="?attr/actionBarSize"
        android:layout_height="match_parent"/>

    <LinearLayout
        android:id="@+id/top"
        android:layout_width="match_parent"
        android:layout_height="52dp"
        android:background="#f00"
        android:orientation="vertical">
    </LinearLayout>

    <LinearLayout
        android:id="@+id/buttom"
        android:layout_width="match_parent"
        android:layout_height="52dp"
        android:layout_gravity="bottom"
        android:background="#f00"
        android:orientation="vertical">
    </LinearLayout>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|right"
        android:layout_marginBottom="40dp"
        app:borderWidth="0dp"
        />
</FrameLayout>