Java下载文件（流的形式）

    @RequestMapping("download")
    @ResponseBody
    public void download(HttpServletResponse response, Integer userId, String fileUrl) { 
        try {
            File file=new File(fileUrl);
            String filename=file.getName();
            // 以流的形式下载文件。
            InputStream fis = new BufferedInputStream(new FileInputStream(fileUrl));
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();
            // 清空response
            response.reset();
            
            response.setContentType("application/octet-stream;charset=UTF-8");
            String fileName = new String(filename.getBytes("gb2312"), "iso8859-1");
            response.setHeader("Content-disposition", "attachment;filename=" + fileName);
            OutputStream ouputStream = response.getOutputStream();
            ouputStream.write(buffer);
            ouputStream.flush();
            ouputStream.close(); 
        } catch (Exception e) {
            e.printStackTrace();
            logger.error("文件下载出现异常", e); 
        } 
    }