Delphi OleVariant与 String 、TMemoryStream、Recordset 的相互转换

Delphi OleVariant与 String 、TMemoryStream、Recordset 的相互转换

1、OleVariant与 String

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//OLEVARIANT转STRING function OleDataToText(const AData: OleVariant): string; var   nSize: Integer;   pData: Pointer; begin   if AData = Null then     Result := ''   else   begin     nSize := VarArrayHighBound(AData, 1) - VarArrayLowBound(AData, 1) + 1;     SetLength(Result, nSize);     pData := VarArrayLock(AData);     try       Move(pData^, Pchar(Result)^, nSize);     finally       VarArrayUnlock(AData);     end;   end; end;

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//string 与 OleVariant function TextToOleData(const AText: string): OleVariant; var   nSize: Integer;   pData: Pointer; begin   nSize := Length(AText);   if nSize = 0 then     Result := Null   else   begin     Result := VarArrayCreate([0, nSize - 1], varByte);     pData := VarArrayLock(Result);     try       Move(Pchar(AText)^, pData^, nSize);     finally       VarArrayUnlock(Result);     end;   end; end;

2、OleVariant与 TMemoryStream　

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//OLEVariant转TMemoryStream: function MemoryStreamToOleVariant(Strm: TMemoryStream): OleVariant; var   Data: PByteArray; begin   Result := VarArrayCreate([0, Strm.Size - 1], varByte);   Data := VarArrayLock(Result);   try     Strm.Position := 0;     Strm.ReadBuffer(Data^, Strm.Size);   finally     VarArrayUnlock(Result);   end; end;<br> // function OleVariantToMemoryStream(OV: OleVariant): TMemoryStream; var   Data: PByteArray;   Size: integer; begin   Result := TMemoryStream.Create;   try     Size := VarArrayHighBound(OV, 1) - VarArrayLowBound(OV, 1) + 1;     Data := VarArrayLock(OV);     try       Result.Position := 0;       Result.WriteBuffer(Data^, Size);     finally       VarArrayUnlock(OV);     end;   except     Result.Free;     Result := nil;   end; end;

3、OleVariant与 Recordset

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function RecordsetToVariant(const Recordset: _Recordset; var Stream: OleVariant): boolean; var   RS: OleVariant;   vData: TMemoryStream; begin   Result := false;   if Recordset = nil then     Exit;   vData := TMemoryStream.Create;   try     RS := CreateOleObject('ADODB.Recordset');     RS := Recordset;     RS.Save(TStreamAdapter.Create(vData) as IUnknown, adPersistADTG);     vData.Position := 0;     Result := true;     Stream := MemoryStreamToOleVariant(vData);   except     on E: Exception do     begin       RS := E.Message;       Stream := RS;       Result := False;     end;   end; end;<br> // function RecordsetFromVariant(vdata: OleVariant): _Recordset; var   RS: OleVariant;   Stream: TMemoryStream; begin   Result := nil;   Stream := TMemoryStream.Create;   Stream := OleVariantToMemoryStream(vdata);   if Stream.Size < 1 then     Exit;   try     Stream.Position := 0;     RS := CreateOleObject('ADODB.Recordset');     RS.Open(TStreamAdapter.Create(Stream) as IUnknown);     Result := IUnknown(RS) as _Recordset;   finally     //   end; end;

　　

　　

　

创建时间：2021.02.05　　更新时间：