将数据集的数据导出Excel

{ 背景：今天要把DataSet导入Excel，查询以前的贴子，一部分用Ole，速度太慢，
一部分用ADO连接到Excel文件，也很慢，一气之下把DBGrigEh的导出部分改了出来，
欢迎大家指教、改进。
功能：将数据集的数据导入Excel;
用法：With TDS2Excel.Create(TDataSet(ADOQuery1)) do
Try
Save2File(SaveDialog1.FileName, True);
finally
Free;
end;
作者：Caidao (核心代码来自Ehlib)
时间：2003-04-09
地点：汕头
}

unit UntObject;

interface

Uses
DB, Classes;

var
CXlsBof: array[0..5] of Word = ($809, 8, 0, $10, 0, 0);
CXlsEof: array[0..1] of Word = ($0A, 00);
CXlsLabel: array[0..5] of Word = ($204, 0, 0, 0, 0, 0);
CXlsNumber: array[0..4] of Word = ($203, 14, 0, 0, 0);
CXlsRk: array[0..4] of Word = ($27E, 10, 0, 0, 0);
CXlsBlank: array[0..4] of Word = ($201, 6, 0, 0, $17);

Type
TDS2Excel = Class(TObject)
Private
FCol: word;
FRow: word;
FDataSet: TDataSet;
Stream: TStream;
FWillWriteHead: boolean;
FBookMark: TBookmark;
procedure IncColRow;
procedure WriteBlankCell;
procedure WriteFloatCell(const AValue: Double);
procedure WriteIntegerCell(const AValue: Integer);
procedure WriteStringCell(const AValue: string);
procedure WritePrefix;
procedure WriteSuffix;
procedure WriteTitle;
procedure WriteDataCell;

procedure Save2Stream(aStream: TStream);
Public
procedure Save2File(FileName: string; WillWriteHead: Boolean);
Constructor Create(aDataSet: TDataSet);
end;

implementation

uses SysUtils;

Constructor TDS2Excel.Create(aDataSet: TDataSet);
begin
inherited Create;
FDataSet := aDataSet;
end;

procedure TDS2Excel.IncColRow;
begin
if FCol = FDataSet.FieldCount - 1 then
begin
Inc(FRow);
FCol :=0;
end
else
Inc(FCol);
end;

procedure TDS2Excel.WriteBlankCell;
begin
CXlsBlank[2] := FRow;
CXlsBlank[3] := FCol;
Stream.WriteBuffer(CXlsBlank, SizeOf(CXlsBlank));
IncColRow;
end;

procedure TDS2Excel.WriteFloatCell(const AValue: Double);
begin
CXlsNumber[2] := FRow;
CXlsNumber[3] := FCol;
Stream.WriteBuffer(CXlsNumber, SizeOf(CXlsNumber));
Stream.WriteBuffer(AValue, 8);
IncColRow;
end;

procedure TDS2Excel.WriteIntegerCell(const AValue: Integer);
var
V: Integer;
begin
CXlsRk[2] := FRow;
CXlsRk[3] := FCol;
Stream.WriteBuffer(CXlsRk, SizeOf(CXlsRk));
V := (AValue shl 2) or 2;
Stream.WriteBuffer(V, 4);
IncColRow;
end;

procedure TDS2Excel.WriteStringCell(const AValue: string);
var
L: Word;
begin
L := Length(AValue);
CXlsLabel[1] := 8 + L;
CXlsLabel[2] := FRow;
CXlsLabel[3] := FCol;
CXlsLabel[5] := L;
Stream.WriteBuffer(CXlsLabel, SizeOf(CXlsLabel));
Stream.WriteBuffer(Pointer(AValue)^, L);
IncColRow;
end;

procedure TDS2Excel.WritePrefix;
begin
Stream.WriteBuffer(CXlsBof, SizeOf(CXlsBof));
end;

procedure TDS2Excel.WriteSuffix;
begin
Stream.WriteBuffer(CXlsEof, SizeOf(CXlsEof));
end;

procedure TDS2Excel.WriteTitle;
var
n: word;
begin
for n := 0 to FDataSet.FieldCount - 1 do
WriteStringCell(FDataSet.Fields[n].FieldName);
end;

procedure TDS2Excel.WriteDataCell;
var
n: word;
begin
WritePrefix;
if FWillWriteHead then WriteTitle;
FDataSet.DisableControls;
FBookMark := FDataSet.GetBookmark;
FDataSet.First;
while not FDataSet.Eof do
begin
for n := 0 to FDataSet.FieldCount - 1 do
begin
if FDataSet.Fields[n].IsNull then
WriteBlankCell
else begin
case FDataSet.Fields[n].DataType of
ftSmallint, ftInteger, ftWord, ftAutoInc, ftBytes:
WriteIntegerCell(FDataSet.Fields[n].AsInteger);
ftFloat, ftCurrency, ftBCD:
WriteFloatCell(FDataSet.Fields[n].AsFloat);
else
WriteStringCell(FDataSet.Fields[n].AsString);
end;
end;
end;
FDataSet.Next;
end;
WriteSuffix;
if FDataSet.BookmarkValid(FBookMark) then FDataSet.GotoBookmark(FBookMark);
FDataSet.EnableControls;
end;

procedure TDS2Excel.Save2Stream(aStream: TStream);
begin
FCol := 0;
FRow := 0;
Stream := aStream;
WriteDataCell;
end;

procedure TDS2Excel.Save2File(FileName: string; WillWriteHead: Boolean);
var
aFileStream: TFileStream;
begin
FWillWriteHead := WillWriteHead;
if FileExists(FileName) then DeleteFile(FileName);
aFileStream := TFileStream.Create(FileName, fmCreate);
Try
Save2Stream(aFileStream);
Finally
aFileStream.Free;
end;
end;

end.

--------------------------------------------------------------------------------

procedure TDS2Excel.Save2File(WillWriteHead: Boolean);
var
SaveDialog1: TSaveDialog;
begin
SaveDialog1 := TSaveDialog.Create(nil);
Try
SaveDialog1.Filter := 'Excel文档|*.xls';
SaveDialog1.InitialDir := 'D:\';
if not SaveDialog1.Execute then exit;
Save2File(SaveDialog1.FileName, WillWriteHead);
Finally
SaveDialog1.Free;
end;
end;