GridView统计数据和修改Cell

代码：

    /**//// <summary>
    /// 绑定数据
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void GridViewXinXiLan_RowDataBound(object sender, GridViewRowEventArgs e)
    ...{

        if (e.Row.RowType == DataControlRowType.DataRow)
        ...{
            totalstock += Convert.ToDecimal(DataBinder.Eval(e.Row.DataItem, "生产量本年实际"));

        }
        else if (e.Row.RowType == DataControlRowType.Footer)
        ...{
            e.Row.Cells[1].Text = "统计";
            e.Row.Cells[1].HorizontalAlign = HorizontalAlign.Right;
            e.Row.Cells[4].Text = totalstock.ToString();
            e.Row.Cells[4].HorizontalAlign = HorizontalAlign.Right;

        }
        
    }

    /**//// <summary>
    /// 修改数据
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void ButtonLoad_Click(object sender, EventArgs e)
    ...{
        // 修改数据
        GridViewXinXiLan.Rows[5].Cells[4].Text = "test";
        GridViewXinXiLan.FooterRow.Cells[4].Text = "统计测试";
    }