以下是一个示例代码，演示如何在水平的RecyclerView中绘制小的居中圆形分隔符：

首先，在您的RecyclerView的适配器中创建一个继承自ItemDecoration的自定义分隔符类：

public class DividerItemDecoration extends RecyclerView.ItemDecoration {
    private int dividerSize;
    private Paint dividerPaint;

    public DividerItemDecoration(Context context) {
        dividerSize = context.getResources().getDimensionPixelSize(R.dimen.divider_size);
        dividerPaint = new Paint();
        dividerPaint.setColor(ContextCompat.getColor(context, R.color.divider_color));
        dividerPaint.setStrokeWidth(dividerSize);
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.right = dividerSize;
    }

    @Override
    public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
        super.onDraw(canvas, parent, state);
        int childCount = parent.getChildCount();
        int left, right, top, bottom;

        for (int i = 0; i < childCount - 1; i++) {
            View child = parent.getChildAt(i);
            left = child.getRight();
            right = left + dividerSize;
            top = child.getTop() + (child.getHeight() - dividerSize) / 2;
            bottom = child.getBottom() - (child.getHeight() - dividerSize) / 2;

            canvas.drawRect(left, top, right, bottom, dividerPaint);
        }
    }
}

然后，在您的Activity或Fragment中，将这个分隔符应用到RecyclerView上：

RecyclerView recyclerView = findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
recyclerView.addItemDecoration(new DividerItemDecoration(this));

请注意，上述代码中的R.dimen.divider_size和R.color.divider_color需要根据您的项目中的实际资源ID进行调整。您可以在dimens.xml和colors.xml文件中定义这些资源。

最后，确保您的RecyclerView的适配器中有足够的项目来绘制分隔符。在示例代码中，我们使用了childCount - 1来避免在最后一个项目之后绘制分隔符。

希望这个示例对您有所帮助！