ASP.net中GridView合并单元格

/// <summary>
        /// 合并单元格
        /// </summary>
        /// <param name="gv">需要合并的风格视图</param>
        /// <param name="rowCount">需要合并的列</param>
        private void GroupGridView(GridView gv, int rowCount)
        {
            string str = "";
            int i = 0;
            int a1 = 0;
            int rowSpanCount = 2;
            foreach (GridViewRow row in gv.Rows)
            {
                if (str == row.Cells[rowCount].Text)
                {
                    gv.Rows[a1 - 1].Cells[rowCount].RowSpan = rowSpanCount++;
                    gv.Rows[i].Cells[rowCount].Visible = false;
                }
                else
                {
                    rowSpanCount = 2;
                    a1 = i + 1;
                }
                str = row.Cells[rowCount].Text;

                i++;
            }
        }