扩展ADODataSet功能，增加LoadFromStream、SaveToStream、LoadFromString、SaveToString等方法：
unit MyADODataSet; interface uses Classes, ADODB, ADOInt, Variants; type TMyADODataSet = class(TADODataSet) public function LoadFromStream(Stream: TStream): Boolean; function SaveToStream(Stream: TStream): Boolean; function LoadFromString(const Value: string): Boolean; function SaveToString(var Value: string): Boolean; end; procedure Register; implementation type Recordset25 = interface(_Recordset) ['{00000556-0000-0010-8000-00AA006D2EA4} '] procedure Save(Destination: OleVariant; PersistFormat: PersistFormatEnum); safecall; end; function TMyADODataSet.LoadFromStream(Stream: TStream): Boolean; var mRecordSet: _Recordset; begin Result := False; Close; DestroyFields; mRecordSet := CoRecordset.Create; try if mRecordSet.State = adStateOpen then mRecordSet.Close; Stream.Position := 0; mRecordSet.Open(TStreamAdapter.Create(Stream) as IUnknown, EmptyParam, adOpenStatic, adLockBatchOptimistic, adAsyncExecute); Stream.Position := 0; if not mRecordSet.BOF then mRecordSet.MoveFirst; RecordSet := mRecordSet; inherited OpenCursor(False); Resync([]); Result := True; except // end; end; function TMyADODataSet.SaveToStream(Stream: TStream): Boolean; var mRecordSet: Recordset25; begin Result := False; if Recordset = nil then Exit; if Recordset.QueryInterface(Recordset25, mRecordSet) = 0 then try Stream.Position := 0; mRecordSet.Save(TStreamAdapter.Create(Stream) as IUnknown, adPersistXML); Stream.Position := 0; Result := True; except // end; end; function TMyADODataSet.LoadFromString(const Value: string): Boolean; var mStream: TStringStream; begin Result := False; if Value = ' ' then Exit; mStream := TStringStream.Create(UTF8Encode(Value)); try LoadFromStream(mStream); Result := True; finally mStream.Free; end; end; function TMyADODataSet.SaveToString(var Value: string): Boolean; var mStream: TStringStream; begin Result := False; mStream := TStringStream.Create(' '); try SaveToStream(mStream); mStream.Position := 0; Value := Utf8ToAnsi(mStream.ReadString(mStream.Size)); Result := True; finally mStream.Free; end; end; procedure Register; begin RegisterComponents('Standard ', [TMyADODataSet]); end; end.
