利用字节流读取csv文件

// csv下载
    @RequestMapping(value = "/selectTaskDownFile.do", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<byte[]> selectTaskDownFile(HttpServletRequest req, HttpServletResponse res) {

        Map<String, Object> map = new HashMap<>();
        String path = req.getParameter("path");
        try {

            // ServletContext servletContext = req.getServletContext();
            String fileName = path.replaceAll("\\\\", "/").split("/")[path.replaceAll("\\\\", "/").split("/").length
                    - 1];
            // String realPath = servletContext.getRealPath(path);// 得到文件所在位置
            String realPath = path.replaceAll("\\\\", "/");// 得到文件所在位置
            InputStream in = new FileInputStream(new File(realPath));// 将该文件加入到输入流之中
            byte[] body = null;
            body = new byte[in.available()];// 返回下一次对此输入流调用的方法可以不受阻塞地从此输入流读取（或跳过）的估计剩余字节数
            in.read(body);// 读入到输入流里面
            fileName = new String(fileName.getBytes("gbk"), "iso8859-1");// 防止中文乱码
            HttpHeaders headers = new HttpHeaders();// 设置响应头
            headers.add("Content-Disposition", "attachment;filename=" + fileName);
            HttpStatus statusCode = HttpStatus.OK;// 设置响应吗
            ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(body, headers, statusCode);
            return response;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }

    }