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();
  }
}