/**
 * 用來處理 如果是Footer 是 GridView 的情況下 最後佔一個 gridview item
 */
@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);
    RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();

    if (manager instanceof GridLayoutManager) {
        final 
 
GridLayoutManager gridManager = ((GridLayoutManager) manager);
        gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                // 如果當前是footer的位置，那麼該item佔據2個單元格，正常情況下佔據1個單元格
                return getItemViewType(position) == FOOTER 
 
? gridManager.getSpanCount() : 1;
            }
        });
    }
}