public string ExportExcel( DataSet ds,string saveFileName)        {            try            {                if (ds == null)                     return "数据库为空";                         bool fileSaved = false;                Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();                if (xlApp == null)                {                    return "无法创建Excel对象，可能您的机子未安装Excel";                }                Microsoft.Office.Interop.Excel.Workbooks workbooks = xlApp.Workbooks;                Microsoft.Office.Interop.Excel.Workbook workbook = workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);                Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[1];//取得sheet1                //写入字段                for (int i = 0; i < ds.Tables[0].Columns.Count; i++)                {                    worksheet.Cells[1, i + 1] = ds.Tables[0].Columns[i].ColumnName;                }                //写入数值                for (int r = 0; r < ds.Tables[0].Rows.Count; r++)                {                    for (int i = 0; i < ds.Tables[0].Columns.Count; i++)                    {                        worksheet.Cells[r + 2, i + 1] = ds.Tables[0].Rows[r][i];                    }                    System.Windows.Forms.Application.DoEvents();                }                worksheet.Columns.EntireColumn.AutoFit();//列宽自适应。                if (saveFileName != "")                {                    try                    {                        workbook.Saved = true;                        workbook.SaveCopyAs(saveFileName);                        fileSaved = true;                    }                    catch (Exception ex)                    {                        fileSaved = false;                        MessageBox.Show("导出文件时出错,文件可能正被打开！\n" + ex.Message);                    }                }                else                {                    fileSaved = false;                }                xlApp.Quit();                GC.Collect();//强行销毁                if (fileSaved && System.IO.File.Exists(saveFileName)) System.Diagnostics.Process.Start(saveFileName); //打开EXCEL                return "成功保存到Excel";            }            catch (Exception ex)            {                return ex.ToString();            }        }