force download in servlet

ForceDownload.java

public class DownloadAction extends Action {
   public void downloadXls(HttpServletRequest request,HttpServletResponse response){
      WritableWorkbook workbook = Workbook.createWorkbook(response.getOutputStream());
      //....Genrate Xls
      response.setHeader("Expires", "0");
      response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
      response.setHeader("Pragma", "public");
      response.setContentType("application/vnd.ms-excel");
      response.setCharacterEncoding("UTF-8");
      //starts with "attachment;" means force download,otherwise "inline;" instaed means view in browser
      if(request.getHeader("User-Agent").contains("Trident/7.0") || request.getHeader("User-Agent").contains("MSIE")){
        response.setHeader("Content-Disposition","attachment; filename="+URLEncoder.encode("資料.xls","utf-8"));
      } else {
        response.setHeader("Content-Disposition", String.format("attachment; filename=\"%s.xls\"",
                        MimeUtility.encodeWord("資料")));
      }
      response.setHeader("Content-Transfer-Encoding", "binary");
      response.setHeader("Connection", "close");
      workbook.write();
      workbook.close();
   }

  public void downloadPdf(HttpServletRequest request,HttpServletResponse response){
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    Document document = new Document(PageSize.A4);
    PdfWriter writer = PdfWriter.getInstance(document, baos);
    //... generate Pdf document
    response.setHeader("Expires", "0");
    response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
    response.setHeader("Pragma", "public");
    response.setContentType("application/pdf");
    response.setCharacterEncoding("UTF-8");
    if(request.getHeader("User-Agent").contains("Trident/7.0") || request.getHeader("User-Agent").contains("MSIE")){
       response.setHeader("Content-Disposition","attachment; filename="+URLEncoder.encode("資料.pdf","utf-8"));
    } else {
       response.setHeader("Content-Disposition", String.format("attachment; filename=\"%s.pdf\"",
            MimeUtility.encodeWord("資料")));
    }
    response.setContentLength(baos.size());
    try (OutputStream os = response.getOutputStream()) {
      baos.writeTo(os);
      os.flush();
    }
  }
}