TOpenDialog/zh CN

procedure TForm1.Button1Click(Sender: TObject);
var
  s:String;
begin
  try
  OpenDialog1.Execute;
  s := OpenDialog1.FileName;
  Form1.Caption  := s;
  Memo1.Lines.LoadFromFile(s);
  except
   on E: Exception do
    //ShowMessage( 'Error: '+ E.ClassName + #13#10 + E.Message );
    ShowMessage('忘记选择文件或者选择的文件不存在');
  end;
end;