将dataset里的数据导出excel，并保存excel表

用Servers组件，如果不将控件free掉，内存里有excel.exe进程。这样
会导致excel不能正常工作。下面一个function是将dataset里的数据导出excel，并保存excel表，大家有空可以加个数据统计什么的。

procedure TFrmMain.WriteExcel(AdsData: TADODataSet; sName, Title: string);
var
  ExcelApplication1: TExcelApplication;
  ExcelWorksheet1: TExcelWorksheet;
  ExcelWorkbook1: TExcelWorkbook;
  i, j: integer;
  filename: string;
begin
  filename := concat(extractfilepath(application.exename), sName, '.xls');
  try
    ExcelApplication1 := TExcelApplication.Create(Application);
    ExcelWorksheet1 := TExcelWorksheet.Create(Application);
    ExcelWorkbook1 := TExcelWorkbook.Create(Application);
    ExcelApplication1.Connect;
  except
    Application.Messagebox('Excel 没有安装!', 'Hello', MB_ICONERROR + mb_Ok);
    Abort;
  end;
  try
    ExcelApplication1.Workbooks.Add(EmptyParam, 0);
    ExcelWorkbook1.ConnectTo(ExcelApplication1.Workbooks[1]);
    ExcelWorksheet1.ConnectTo(ExcelWorkbook1.Worksheets[1] as _worksheet);
    AdsData.First;
    for j := 0 to AdsData.Fields.Count - 1 do
      begin
        ExcelWorksheet1.Cells.item[3, j + 1] := AdsData.Fields[j].DisplayLabel;
        ExcelWorksheet1.Cells.item[3, j + 1].font.size := '10';
      end;
    for i := 4 to AdsData.RecordCount + 3 do
      begin
        for j := 0 to AdsData.Fields.Count - 1 do
          begin
            ExcelWorksheet1.Cells.item[i, j + 1] :=
                AdsData.Fields[j].Asstring;
            ExcelWorksheet1.Cells.item[i, j + 1].font.size := '10';
          end;
        AdsData.Next;
      end;
    ExcelWorksheet1.Columns.AutoFit;
    ExcelWorksheet1.Cells.item[1, 2] := Title;
    ExcelWorksheet1.Cells.Item[1, 2].font.size := '14';
    ExcelWorksheet1.SaveAs(filename);
    Application.Messagebox(pchar('数据成功导出' + filename), 'Hello',
      mb_Ok);
  finally
    ExcelApplication1.Disconnect;
    ExcelApplication1.Quit;
    ExcelApplication1.Free;
    ExcelWorksheet1.Free;
    ExcelWorkbook1.Free;
  end;
end;