Android RecyclerView实现九宫格横向左右滑动

实现九宫格横向左右滑动的功能，可以使用 RecyclerView 和 GridLayoutManager 来实现。以下是具体步骤：

1. 在布局文件中，添加 RecyclerView 控件：

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recycler_view"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:scrollbars="horizontal" />

2. 在代码中，初始化 RecyclerView 和 GridLayoutManager，并设置相关属性：

RecyclerView recyclerView = findViewById(R.id.recycler_view);
GridLayoutManager layoutManager = new GridLayoutManager(this, 3); // 设置列数为3
layoutManager.setOrientation(RecyclerView.HORIZONTAL); // 设置水平滚动
recyclerView.setLayoutManager(layoutManager);

int spacing = getResources().getDimensionPixelSize(R.dimen.grid_spacing); // 设置item之间的间距
recyclerView.addItemDecoration(new GridSpacingItemDecoration(3, spacing, true)); // 通过自定义ItemDecoration来实现

其中，GridSpacingItemDecoration 是自定义的一个 RecyclerView.ItemDecoration，用来设置 item 之间的间距，具体实现如下：

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {

    private int spanCount;
    private int spacing;
    private boolean includeEdge;

    public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
        this.spanCount = spanCount;
        this.spacing = spacing;
        this.includeEdge = includeEdge;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view); // item position
        int column = position % spanCount; // item column

        if (includeEdge) {
            outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
            outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)

            if (position < spanCount) { // top edge
                outRect.top = spacing;
            }
            outRect.bottom = spacing; // item bottom
        } else {
            outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
            outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f /    spanCount) * spacing)
            if (position >= spanCount) {
                outRect.top = spacing; // item top
            }
        }
    }
}

3. 创建 RecyclerView.Adapter 和 RecyclerView.ViewHolder，并在 onBindViewHolder() 方法中设置 item 的内容：

public class GridAdapter extends RecyclerView.Adapter<GridAdapter.GridViewHolder> {

    private List<Integer> dataList; // 数据源

    public GridAdapter(List<Integer> dataList) {
        this.dataList = dataList;
    }

    @NonNull
    @Override
    public GridViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_grid, parent, false);
        return new GridViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull GridViewHolder holder, int position) {
        holder.imageView.setImageResource(dataList.get(position)); // 设置图片资源
    }

    @Override
    public int getItemCount() {
        return dataList.size();
    }

    static class GridViewHolder extends RecyclerView.ViewHolder {
        ImageView imageView;

        GridViewHolder(View itemView) {
            super(itemView);

            imageView = itemView.findViewById(R.id.image_view);
        }
    }
}

4. 最后在 Activity 中设置 RecyclerView 的 adapter：

List<Integer> dataList = new ArrayList<>(); // 数据源
dataList.add(R.drawable.pic1);
dataList.add(R.drawable.pic2);
dataList.add(R.drawable.pic3);
dataList.add(R.drawable.pic4);
dataList.add(R.drawable.pic5);
dataList.add(R.drawable.pic6);
dataList.add(R.drawable.pic7);
dataList.add(R.drawable.pic8);
dataList.add(R.drawable.pic9);

GridAdapter adapter = new GridAdapter(dataList);
recyclerView.setAdapter(adapter);

这样就可以实现九宫格横向左右滑动的效果了。