asp.net DataGridView导出到Excel的三个方法[亲测]

                {   
                    columnTitle += "t";   
                }   
                columnTitle += dgv.Columns[i].HeaderText;   
            }   
            sw.WriteLine(columnTitle);   

            //写入列内容   
            for (int j = 0; j < dgv.Rows.Count; j++)   
            {   
                string columnValue = "";   
                for (int k = 0; k < dgv.Columns.Count; k++)   
                {   
                    if (k > 0)   
                    {   
                        columnValue += "t";   
                    }   
                    if (dgv.Rows[j].Cells[k].Value == null)   
                        columnValue += "";   
                    else  
                        columnValue += dgv.Rows[j].Cells[k].Value.ToString().Trim();