Download server file in browser | Download file on browser

Question

       @RequestMapping(value = "/download1", method = RequestMethod.GET)
        public ResponseEntity<Object> downloadFile() throws IOException
        {
          String filename = "http://k8s-di-..../doc/getfile/path/4960_popo.txt";
      //  String filename = "C:/download-file/pk.txt";
          File file = new File(filename);    //line3......
          InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
        
          HttpHeaders headers = new HttpHeaders();
          headers.add("Content-Disposition",
          String.format("attachment; filename=\"%s\"", 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/txt")).body(resource);

          return responseEntity;
    }

when i use local file i.e("C:/download-file/pk.txt") code will work fine file will download on browser But When i use server file i.t will not work.When i use this url("http://k8s-di-..../doc/getfile/path/4960_popo.txt") line no.3 in file value will show http:\k8s-didi....\doc\getfile\path\4960_popo.txt. This url is correct? Error - (The filename, directory name, or volume label syntax is incorrect) Is there any suggestion please give me. My motive is download file in browser.