간단한 파일 다운로드 서블릿을 구현하는 방법은 무엇입니까?

public class DownloadServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String id = request.getParameter("id");
        // Retrieve file name and type using ID from database
        response.setContentType("fileType");
        response.setHeader("Content-disposition", "attachment; filename=yourcustomfilename.pdf");
        File file = new File("fileName");
        OutputStream out = response.getOutputStream();
        try (FileInputStream in = new FileInputStream(file)) {
            byte[] buffer = new byte[4096];
            int length;
            while ((length = in.read(buffer)) > 0) {
                out.write(buffer, 0, length);
            }
        } finally {
            out.flush();
        }
    }
}