indy idhttp 이용해서 파일 업로드

procedure TForm1.Button1Click(Sender: TObject);
 var
   UploadFile: TIdMultiPartFormDataStream;
   Outputs: TStringStream;
 begin
   if OpenDialog1.Execute then
   begin
     UploadFile := TIdMultiPartFormDataStream.Create;
     Outputs := TStringStream.Create('');
 
     try
       IdHTTP.Request.ContentType := UploadFile.RequestContentType;
 
       UploadFile.AddFormField('Mb_Num', '13');
       UploadFile.AddFile('UploadList', OpenDialog1.FileName, 'application/unknown');
       UploadFile.Position := 0;
 
       try
         IdHTTP.Post( 'http://www.xxxxx.com/xxxx.asp', UploadFile, Outputs);
       except
         ShowMessage('포스트 에러');
       end;
 
       ShowMessage( Outputs.DataString );
     finally
       UploadFile.Free;
       Outputs.Free;
     end;
   end;
 end;