ADO特有的流化和还原 

{*******************************************************}

{ }

{ ADO 数据流化 }

{ }

{ 版权所有 (C) 2013 YangYxd }

{ }

{*******************************************************}

{ ado数据集流化

Rs: TADOQuery;

M: TMemoryStream;

Rs.SQL.Text := 'Select * from TBApp';

Rs.Open;

Rs.First;

M := TMemoryStream.Create;

YxdAdoStream.DataSetToStream(Rs, M);

m.SaveToFile(SoftPath + 'tbapp.data');

}

{ 从流中还原ADO数据集

Rs := TADOQuery.Create(Self);

try

t1 := GetTickCount;

M.Position := 0;

YxdAdoStream.StreamToDataSet(M, Rs);

t1 := GetTickCount - t1;

finally

FreeAndNil(M);

Rs.Free;

end;

}

unit YxdAdoStream;

interface

{$IF RTLVersion>=24}

{$LEGACYIFEND ON}

{$IFEND}

{$IF defined(FPC)}

{$DEFINE USEINLINE}

{$IFEND}

{$IF RTLVersion>=18}

{$DEFINE USEINLINE}

{$IFEND}

uses

Windows, Classes, Sysutils, comobj, ActiveX,

{$IFDEF USEINLINE}Ole2, {$ENDIF}

adoint, adodb, db;

{$IFNDEF USEINLINE}

const

IID_IPersistStream: TGUID = (

D1:$00000109;D2:$0000;D3:$0000;D4:($C0,$00,$00,$00,$00,$00,$00,$46));

IID_IStream: TGUID = (

D1:$0000000C;D2:$0000;D3:$0000;D4:($C0,$00,$00,$00,$00,$00,$00,$46));

{$ENDIF}

function CheckADODataSet(const ADataSet: TDataSet): TCustomADODataSet;

/// <summary>

/// 从流中加载数据集对象

/// </summary>

procedure StreamToDataSet(AStream: TStream; ADataSet: TCustomADODataSet);

/// <summary>

/// 将数据集写入流中

/// </summary>

procedure DataSetToStream(ADataSet: TCustomADODataSet; AStream: TStream);

implementation

resourcestring

SInvalidDataSet = '参数DataSet必须是AdoDataSet';

function CheckADODataSet(const ADataSet: TDataSet): TCustomADODataSet;

begin

if not (ADataSet is TCustomADODataSet) then

raise Exception.Create(SInvalidDataSet)

else

Result := TCustomADODataSet(ADataSet);

end;

procedure DataSetToStream(ADataSet:TCustomADODataSet; AStream:TStream);

var

ATemp: TStreamAdapter;

ADataSetStream: IPersistStream;

AIntf: IStream;

ARecs: OleVariant;

ASet: _Recordset;

begin

ASet := ADataSet.Recordset;

while (ASet.State = adStateClosed) do begin //如果执行存储过程一类的脚本,可能存在多个结果集

ASet := ADataSet.Recordset.NextRecordset(ARecs);

if ASet = nil then

raise Exception.Create('数据集无数据');

end;

OleCheck(ASet.QueryInterface(System.PGuid(@IID_IPersistStream)^, ADataSetStream));

ATemp := TStreamAdapter.Create(AStream);

try

ATemp.GetInterface(System.PGuid(@IID_IStream)^, AIntf);

OleCheck(OleSaveToStream(ADataSetStream, AIntf));

finally

ASet._Release;

ATemp.FreeInstance;

AIntf := nil;

end;

end;

procedure StreamToDataSet(AStream:TStream; ADataSet: TCustomADODataSet);

var

ATemp: Classes.TStreamAdapter;

ARecordSet: ADOInt.Recordset;

AIntf: IStream;

begin

ATemp := Classes.TStreamAdapter.Create(AStream);

try

ADataSet.LockType := ltBatchOptimistic;

ADataSet.Recordset := nil;

try

ATemp.GetInterface(System.PGuid(@IID_IStream)^, AIntf);

ComObj.OleCheck({$IFDEF USEINLINE}Ole2.{$ENDIF}OleLoadFromStream(AIntf,

{$IFDEF USEINLINE}Ole2.{$ENDIF}PGuid(@AdoInt.IID__Recordset)^, ARecordset));

ADataSet.Recordset := ARecordSet;

except

OutputDebugString(PChar(Exception(ExceptObject).Message));

end;

finally

ATemp.FreeInstance;

AIntf := nil;

end;

end;

end.