RecyclerView 多布局实现、动态设置布局管理器、StaggeredGridLayoutManager占满一行_动态设置staggeredgridlayoutmanager的数量

RecyclerView实现多种item布局

1:动态改变每一行的列数（动态控制布局管理器）：

重写adpater中的onAttachedToRecyclerView()方法：

动态改变布局管理器调整item行数：
@Override //动态设置布局管理器行数
public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {
    RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();

    if (manager instanceof GridLayoutManager && "score".equals(type)) {
        final GridLayoutManager gridManager = ((GridLayoutManager) manager);
        gridManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                if (getItemViewType(position) == TYPE_HEADER) {
                    return 2; //返回2展示一行
                } else {
                    return 1;//返回1展示两行
                }

            }
        });
    }
}
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注意：这个getSpanSize()方法返回值并不是要显示的列数。解释：getSpanSize返回值不是表示控制每行有几列，而是当前这个Item占这一行得几列（ 参考文章

2:解决StaggeredGridLayoutManager占满一行：

重写adpater中的onViewAttachedToWindow()方法：

//  解决StaggeredGridLayoutManager占满一行
    @Override
    public void onViewAttachedToWindow(RecyclerView.ViewHolder holder) {
        super.onViewAttachedToWindow(holder);
        int type = holder.getItemViewType();
        if (type == TYPE_HEADER) { //如果类型为头部就占满一行
            ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
            if (lp instanceof StaggeredGridLayoutManager.LayoutParams) {
                StaggeredGridLayoutManager.LayoutParams p =
                        (StaggeredGridLayoutManager.LayoutParams) lp;
                p.setFullSpan(true);
            }
        }
    }
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3.防止第一行到顶部有空白区域

StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
        //防止第一行到顶部有空白区域
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                layoutManager.invalidateSpanAssignments();
            }
        });
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