RecyclerView滚动流畅度优化

方法一：

// Adapter中添加如下代码
public abstract class RecyclerBaseAdapter extends RecyclerView.Adapter {
    protected boolean isScrolling = false;
    public void setScrolling(boolean scrolling) {
        isScrolling = scrolling;
    }
}

// 在子Adapter中的onBind里进行控制
public class SubRecyclerViewAdapter extends BaseRecyclerViewAdapter {
    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
        RecyclerViewHolder holder = (RecyclerViewHolder) viewHolder;
  
        if (!TextUtils.isEmpty(data.getAvatarUrl()) && !isScrolling) {
            // 加载跟新数据
        } else {
            holder.avatarImg.setImageResource(占位图);
        }
        super.onBindViewHolder(holder, position);
    }
}

// 外部监听
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        // State的三种状态：SCROLL_STATE_IDLE（静止）、SCROLL_STATE_DRAGGING（上升）、SCROLL_STATE_SETTLING（下落）
        if (newState == SCROLL_STATE_IDLE) { // 滚动静止时才加载图片资源，极大提升流畅度
            mRecyclerViewAdapter.setScrolling(false);
           //简单的形式可以使用  notify调用后onBindViewHolder会响应调用
           //mRecyclerViewAdapter.notifyDataSetChanged(); 
        } else {
            mRecyclerViewAdapter.setScrolling(true);
        }
        super.onScrollStateChanged(recyclerView, newState);
    }
});

方法二：
使用GestureDetector.OnGestureListener监听

public interface OnGestureListener {
        boolean onDown(MotionEvent var1);
 
        void onShowPress(MotionEvent var1);
 
        boolean onSingleTapUp(MotionEvent var1);
 
        boolean onScroll(MotionEvent var1, MotionEvent var2, float var3, float var4);
 
        void onLongPress(MotionEvent var1);
 
        boolean onFling(MotionEvent var1, MotionEvent var2, float var3, float var4)
}

@Override
public boolean onFling(MotionEvent motionEvent, MotionEvent motionEvent1, float v, float v1) {
        if(Math.abs(v1) > 4000){
            mAdapter.setScrolling(true);
        }
        return false;
}

onScrolled方法的作用，如果快速的在屏幕上向下或向上滑动，onFling可以监听到v1大于4000，并且onScrollStateChanged的RecyclerView.SCROLL_STATE_IDLE也会有监听，所以加一个额外条件，如果列表没有任何滚动，则不做任何操作

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        if(dy != 0){
             scrlled = true;
        }      
}

@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
      switch (newState) {                
          // The RecyclerView is not currently scrolling.
          case RecyclerView.SCROLL_STATE_IDLE:               
               if(mAdapter.getScrolling() && scrlled) {
                    //对于滚动不加载图片的尝试
                   mAdapter.setScrolling(false);
                   mAdapter.notifyDataSetChanged();
                }
            scrlled = false;
            break;
      }
      super.onScrollStateChanged(recyclerView, newState);          
}