[DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern int GetWindowThreadProcessId(IntPtr hwnd, out int ID);
        private void ExportToExcel(string fielName)
        {
            //實例化一個Excel.Application對象   
            Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.Application();

            try
            {
                if (dgv_Result.DataSource == null)
                    return;
                if (dgv_Result.Rows.Count == 0)
                    return;

                //新增加一個工作簿，Workbook是直接保存，不會彈出保存對話框，加上Application會彈出保存對話框，值為false會報錯   
                Microsoft.Office.Interop.Excel.Workbook xlBook = excel.Workbooks.Add(true);

                //1.添加表頭
                excel.Cells[1, 1] = tyclass;
                for (int i = 0; i < dgv_Result.Columns.Count; i++)
                {

                    excel.Cells[2, i + 1] = dgv_Result.Columns[i].Name;
                }

                #region 2.實現Excel多維表頭 采用合并單元格的方式
                Microsoft.Office.Interop.Excel.Worksheet sheet = (Microsoft.Office.Interop.Excel.Worksheet)xlBook.ActiveSheet;
                Microsoft.Office.Interop.Excel.Range excelRange = sheet.get_Range(sheet.Cells[1, 1], sheet.Cells[1, 2]);
                Microsoft.Office.Interop.Excel.Range excelRange1 = sheet.get_Range(sheet.Cells[1, 3], sheet.Cells[1, 4]);
                Microsoft.Office.Interop.Excel.Range excelRange2 = sheet.get_Range(sheet.Cells[1,5], sheet.Cells[1, 6]);
                Microsoft.Office.Interop.Excel.Range excelRange3 = sheet.get_Range(sheet.Cells[1,7], sheet.Cells[1, 8]);
                Microsoft.Office.Interop.Excel.Range excelRange4 = sheet.get_Range(sheet.Cells[1, 2], sheet.Cells[1, 3]);
                Microsoft.Office.Interop.Excel.Range excelRange5 = sheet.get_Range(sheet.Cells[1, 6], sheet.Cells[1, 7]);
                Microsoft.Office.Interop.Excel.Range excelRange6 = sheet.get_Range(sheet.Cells[1, 4], sheet.Cells[1,5]);
                excelRange.Merge(excelRange.MergeCells);
                excelRange1.Merge(excelRange1.MergeCells);
                excelRange4.Merge(excelRange4.MergeCells);
                excelRange2.Merge(excelRange2.MergeCells);
                excelRange3.Merge(excelRange3.MergeCells);
                excelRange5.Merge(excelRange5.MergeCells);
                excelRange6.Merge(excelRange6.MergeCells);
                Microsoft.Office.Interop.Excel.Range columnRange = sheet.get_Range("A1", "H2");   //得到  Range 范圍  A-H 表示1-8列，1-2表示跨幾行
                 columnRange.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;
                 columnRange.Font.Size = 10;
                 columnRange.Font.Bold = true;

                #endregion

               
                #region 3.添加行數據，直接給Range賦值可提高效率

                 Microsoft.Office.Interop.Excel.Range range = sheet.get_Range("A3", "H" + (dgv_Result.Rows.Count + 2).ToString());   //得到  Range 范圍
                string[,] AryData = new string[dgv_Result.Rows.Count-1, dgv_Result.Columns.Count];
                for (int i = 0; i < dgv_Result.Rows.Count - 1; i++)
                {
                    for (int j = 0; j < dgv_Result.Columns.Count; j++)
                    {

                        AryData[i,j] = dgv_Result.Rows[i].Cells[j].Value.ToString();
                    }
                }
                range.Value2 = AryData;
                range.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;
                #endregion

                sheet.Cells.Columns.AutoFit();//設置Excel表格的  列寬
                excel.SheetsInNewWorkbook = 1;//設置Excel單元格對齊方式
                excel.DisplayAlerts = false; //設置禁止彈出保存和覆蓋的詢問提示框   
                excel.AlertBeforeOverwriting = false;
                //保存excel文件   
                xlBook.SaveAs(fielName, Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookNormal, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
                MessageBox.Show("導出成功！", "提示");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "錯誤提示");
            }
            finally
            {
                IntPtr pt = new IntPtr(excel.Hwnd);
                int k = 0;
                GetWindowThreadProcessId(pt, out k);
                System.Diagnostics.Process p = System.Diagnostics.Process.GetProcessById(k);
                p.Kill();

            }

        }