下载文件的写法

    @GetMapping("/download")
    public void download(String fid, HttpServletResponse response) throws Exception {
        if (StringUtils.isBlank(fid)) {
            throw new AIPGException("文件ID为空");
        }
        long id = Long.parseLong(fid);
        FileInfo fileInfo = fileOperationService.getFileInfo(id);
        if (fileInfo == null) {
            throw new Exception("该文件不存在");
        }
        String fileName = fileInfo.getFileName();
        byte[] data = fileOperationService.download(id);
        response.setContentType("application/octet-stream");//告诉浏览器输出内容为流
        fileName = new String(fileName.getBytes(), "utf-8");
        response.setHeader("Content-disposition", "attachment;filename=" + fileName);
        try (OutputStream os = response.getOutputStream()) {
            os.write(data);
            os.flush();
        }
    }

　　前台JS代码

 if (layEvent === 'down') {
                location.href = BASE_CONTEXT_PATH + '/file/download.dsr?fid=' + data.FILE_ID;

通过这种方法可以实现对文件的下载功能。