Try this:
@GetMapping("/downloadDOA")
public ResponseEntity<Object> downloadTemplate(HttpServletRequest request, HttpServletResponse response) throws IOException{
String filename = "C://Users//Sai//git//r5//src//main//resources//DOA//DOAtemplate.xls";
File file = new File(filename);
InputStreamResource iresource = new InputStreamResource(new FileInputStream(file));
HttpHeaders headers = new HttpHeaders();
headers.add("Content-Disposition","attachment;filename=" +file.getName());
headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
headers.add("Pragma", "no-cache");
headers.add("Expires", "0");
ResponseEntity<Object> responseEntity = ResponseEntity.ok().headers(headers)
.contentLength(file.length())
.contentType(MediaType.parseMediaType("application/vnd.ms-excel")).body(iresource);
return responseEntity;
}