如何使用原生类ADO中的STREAM对象进行BLOB字段的读写.

Question

请各位高手帮帮忙,分不够可再加,只要能解决问题.

Answer 1

procedure TForm1.BInDBClick(Sender: TObject);
var
  strm:tmemorystream;
  ext:string;
begin
  if imagesee.Picture<>nil then
  begin
    ext:=extractfileext(op.FileName);
    strm:=tmemorystream.Create;
    try
      imagesee.Picture.Graphic.SaveToStream(strm);
      adotable1.Edit;
      strm.Position:=0;
      tblobfield(adotable1.fieldbyname('myimage')).LoadFromStream(strm);
      if uppercase(ext)='.BMP' THEN
        adotable1.FieldByName('isbmp').Value:='1'
      else if (uppercase(ext)='.JPG')OR((uppercase(ext)='.JPEG'))then
        adotable1.FieldByName('isbmp').Value:='0';
      adotable1.Post;
    finally
      strm.Free;
    end;
  end;
end;procedure TForm1.ADOTable1AfterScroll(DataSet: TDataSet);
var
  strm:tadoblobstream;
  jpegimage:tjpegimage;
  bitmap:tbitmap;
begin
  strm:=tadoblobstream.Create(tblobfield(adotable1.FieldByName('myimage')),bmread);
  try
    strm.Position:=0;
    imagesee.Picture.Graphic:=nil;
    if adotable1.FieldByName('isbmp').AsString='1' then
    begin
      bitmap:=tbitmap.Create;
      try
        bitmap.LoadFromStream(strm);
        imagesee.Picture.Graphic:=bitmap;
      finally
        strm.Free;
        bitmap.Free;
      end;
    end
    else if adotable1.FieldByName('isbmp').AsString='0' then
    begin
      jpegimage:=tjpegimage.Create;
      try
        jpegimage.LoadFromStream(strm);
        imagesee.Picture.Graphic:=jpegimage;
      finally
        strm.Free;
        jpegimage.Free;
      end;
    end;
  except
  end;end;
能看懂吗,不动我再写点说明

Answer 2

何必这么复杂,简单点
FieldByName('O_Photo').Assign(Im_Photo.Picture.Graphic);
Im_Photo.Picture.Assign(FieldByName('O_Photo'))

Answer 3

楼上的两个，楼主要的是“原生ADO”的做法……

Answer 4

保存到文件里
var
    PDataValue:Pointer;
   AFields: Fields;
   FieldValue: OleVariant;
   len : integer;
   Stream:TMemoryStream;           FieldValue := AFields[I].Value;
           Stream := TMemoryStream.Create;
            try
              len := AFields[I].ActualSize;
              if VarIsArray(FieldValue) then
              begin
               PDataValue := VarArrayLock(FieldValue);
                try
                Stream.Write(PDataValue^,len);
               Stream.SaveToFile(...);
                finally
                 VarArrayUnlock(FieldValue);
                end;
             end
             else begin
               PDataValue := TVarData(FieldValue).VString;
               Stream.Write(PDataValue^,len);
               Stream.SaveToFile(...);
             end;
            finally
              Stream.Free;
            end;