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);
         }
     }