文件下载

 getHttpServletResponse().setHeader("Cache-Control", "no-cache");        String showname = URLEncoder.encode(f.getName(), "UTF-8");        showname = showname.replace("+", "%20");        getHttpServletResponse().setContentType("application/octet-stream; CHARSET=utf8");        getHttpServletResponse().setHeader("Content-Disposition", "attachment; filename=" + showname);        IOUtils.copy(new FileInputStream(f), getHttpServletResponse().getOutputStream());