通过LinearLayoutManager获取item滑动时位置

LinearLayoutManager linearLayoutManager_content=new LinearLayoutManager(mContext, OrientationHelper.VERTICAL,false);

//  RecyclerView设置滑动监听
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                int firstVisibleItemPosition=0;
                switch (newState){  //判断RecyclerView滑动不同的状态

                    case RecyclerView.SCROLL_STATE_IDLE:
                        //获得当前显示在第一个item的位置 
                        firstVisibleItemPosition = linearLayoutManager_content.findFirstVisibleItemPosition();        
                        break;

                    case RecyclerView.SCROLL_STATE_DRAGGING:
                        //获得当前显示在第一个item的位置 
                        firstVisibleItemPosition = linearLayoutManager_content.findFirstVisibleItemPosition();
                        break;
                }
            }
        });