RecyclerView滑动显示/隐藏控件

复写RecyclerView.OnScrollListener监听事件，使RecyclerView具有滑动显示/隐藏功能

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

/**
 * Created by pc on 2016/7/1.
 */
public abstract class HidingScrollBottomListener extends RecyclerView.OnScrollListener {

    private static final int HIDE_THRESHOLD = 20;//滑动隐藏的阈值

    private int mScrolledDistance = 0;//滑动距离
    private boolean mControlsVisible = true;//控件的显示状态

    /**
    * 向下滑动隐藏控件, 向上滑动显示控件
    * dy, 向下滑动为正值, 向上滑动为负值
    */
    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);

        int firstVisibleItem = ((LinearLayoutManager) recyclerView.getLayoutManager()).findFirstVisibleItemPosition();

        if (firstVisibleItem == 0) {//如果已经滑动到最顶端
            if(!mControlsVisible) {
                onShow();
                mControlsVisible = true;
            }
        } else {//当前Item不是第一条
            if (mScrolledDistance > HIDE_THRESHOLD && mControlsVisible) {//向下滑动
                onHide();
                mControlsVisible = false;
                mScrolledDistance = 0;
            } else if (mScrolledDistance < -HIDE_THRESHOLD && !mControlsVisible) {//向上滑动
                onShow();
                mControlsVisible = true;
                mScrolledDistance = 0;
            }
        }
        if((mControlsVisible && dy>0) || (!mControlsVisible && dy<0)) {
            mScrolledDistance += dy;
        }
    }

    public abstract void onHide();//在onHide()方法里面实现控件隐藏功能
    public abstract void onShow();//在onShow()方法里面实现控件显示功能
}

使用自定义滑动监听事件HidingScrollBottomListener

recyclerView.addOnScrollListener(new HidingScrollBottomListener() {
    @Override
    public void onHide() {
        hideViews();
    }
    @Override
    public void onShow() {
        showViews();
    }
});

private void hideViews() {
    FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) fab.getLayoutParams();//获取控件的布局参数
    int fabBottomMargin = lp.bottomMargin;//与父控件的底部间隔
    fab.animate()//动画
    .translationY(fab.getHeight() + fabBottomMargin)//Y轴上的变换高度
    .setInterpolator(new AccelerateInterpolator(2))//播放速度
    .start();

}

private void showViews() {
    fab.animate()
    .translationY(0)
    .setInterpolator(new DecelerateInterpolator(2))
    .start();
}