下載文件出現內存溢出問題

現場還原，一下是下載大文件出現內存溢出的代碼：

    @RequestMapping(value = "/downLoadBackupFile")
    public ResponseEntity<byte[]> downloadBackupFile(Integer id, HttpServletResponse response) throws Exception{
        String path = eqm.findAddr(id);
        File file = new File(path);
        String fileName = file.getName();
        byte[] body = null;
        InputStream is = new FileInputStream(file);
        body = new byte[is.available()];                                            // 報錯顯示該行出現內存溢出問題，new了一個非常大的byte數組
        is.read(body);
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Disposition", "attchement;filename=" + fileName);
        HttpStatus statusCode = HttpStatus.OK;
        ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(body, headers, statusCode);
        return entity;
    }

應該修改為：

@RequestMapping(value = "/downLoadBackupFile", method = RequestMethod.GET)
    public void downloadBackupFile(Integer id, HttpServletResponse response) throws Exception{
        String path = eqm.findAddr(id);
        File file = new File(path);
        String fileName = file.getName();

        response.reset();
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition", "attchement;filename=" + fileName);
        response.setHeader("Content-Length", file.length() + "");

        InputStream bfis = new BufferedInputStream(new FileInputStream(file));
        OutputStream ops = new BufferedOutputStream(response.getOutputStream());
        byte[] body = new byte[1024];
        int i = -1;
        while ((i = bfis.read(body)) != -1){
            ops.write(body, 0, i);
        }
        bfis.close();
        ops.flush();
        ops.close();
    }