@RequestMapping("/testHttpMessageDown")public ResponseEntity<byte[]> download(HttpServletRequest request) throws IOException {File file = new File(request.getSession().getServletContext().getClassLoader().getResource("test.xlsx").getPath());byte[] body = null;InputStream is = new FileInputStream(file);body = new byte[is.available()];is.read(body);HttpHeaders headers = new HttpHeaders();headers.add("Content-Disposition", "attchement;filename=" + file.getName());HttpStatus statusCode = HttpStatus.OK;ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(body, headers, statusCode);return entity;}

    /** Download a file from *   - inside project, located in resources folder.*   - outside project, located in File system somewhere. */@RequestMapping(value="/download", method = RequestMethod.GET)public void downloadFile(HttpServletRequest request, HttpServletResponse response) throws IOException {File file = new File(request.getSession().getServletContext().getClassLoader().getResource("test.xlsx").getPath());if(!file.exists()){String errorMessage = "Sorry. The file you are looking for does not exist";System.out.println(errorMessage);OutputStream outputStream = response.getOutputStream();outputStream.write(errorMessage.getBytes(Charset.forName("UTF-8")));outputStream.close();return;}String mimeType= URLConnection.guessContentTypeFromName(file.getName());if(mimeType==null){System.out.println("mimetype is not detectable, will take default");mimeType = "application/octet-stream";}System.out.println("mimetype : "+mimeType);response.setContentType(mimeType);/* "Content-Disposition : inline" will show viewable types [like images/text/pdf/anything viewable by browser] right on browser while others(zip e.g) will be directly downloaded [may provide save as popup, based on your browser setting.]*/response.setHeader("Content-Disposition", String.format("inline; filename=\"" + file.getName() +"\""));/* "Content-Disposition : attachment" will be directly download, may provide save as popup, based on your browser setting*///response.setHeader("Content-Disposition", String.format("attachment; filename=\"%s\"", file.getName()));
        response.setContentLength((int)file.length());InputStream inputStream = new BufferedInputStream(new FileInputStream(file));//Copy bytes from source to destination(outputstream in this example), closes both streams.
        FileCopyUtils.copy(inputStream, response.getOutputStream());}