android recyclerview一行多个之间的间距

要设置 RecyclerView 中一行多个 item 之间的间距，可以通过自定义 ItemDecoration 实现。以下是示例代码：

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
            }
        }
    }
}

可以在创建 RecyclerView 时，通过以下代码设置间距：

int spacing = getResources().getDimensionPixelSize(R.dimen.grid_spacing);
recyclerView.addItemDecoration(new GridSpacingItemDecoration(2, spacing, true));

其中，`R.dimen.grid_spacing` 是在 dimens.xml 中定义的间距值，例如：

<dimen name="grid_spacing">16dp</dimen>

这样，就可以设置 RecyclerView 中一行多个 item 之间的间距。