三层结构怎么把图片存入数据库？

Question

1.将应用程序服务器端对应datasetprovider的options的fetchblobondemand选项设为true,因为false情况下,客户端的clientdataset是不取blob数据的.或者在 false情况下用clientdataset的fetchblob方法取得数据库中的数据.
2.源程序如下(win2000/delphi/ocracle)
procedure writetoblobfield;
var
tfStream:TFileStream;
tbStream:TBlobStream;
nbufsize:integer;
pbuf:PChar;
begin
With clientdataset1 do
begin
if Active = false then
Active := true;
Append;
try
tfStream:=TFileStream.Create(FilePath,fmOpenRead);
nbufsize:=tfStream.Size +1;
pbuf:=AllocMem(nbufsize);
tfStream.Read(pbuf^,nbufsize);
tbStream:=TBlobStream.Create((fieldbyname('TestImage') as TBlobField),bmWrite);
tbStream.Seek(0,SoFromBeginning);
tbStream.Write(pbuf^,nbufsize);
finally
tfStream.Free ;
tbStream.Free ;
post;
FreeMem(pbuf,nbufsize);
Active:=False;
end;
end;
end;procedure savetoclient;
var
filebody:tstream;
tempfile:tmemostream;
begin
try
filebody:=clientdataset.createblobstream(Tblobfield,bmread);
filebody.position:=0;
tempfile:=tmemostream.create;
tempfile.loadfromstream(filebody);
tempfile.savetostream(文件名);
finally
tempfile.free;
filebody.frdd;
end;
end;
end; 
 
 

Answer 1

procedure TForm1.btnSaveClick(Sender: TObject);
var ms: TMemoryStream;
bm: TBitmap;
begin
bm := TBitmap.Create;
bm.LoadFromFile('Bitmap File Name');
ClientDataSet1.Edit;
ms := ClientDataSEt.CreateBlobStream('FieldName', bmWrite);
bm.SaveToStream(ms);
ClientDataSet.Post;
ClientDataSet.ApplyUpdatas(-1);
bm.Free;
ms.Free; 
end;