文件下载servlet端代码模版

private void downFile(File file,HttpServletResponse response) throws IOException {// 写数据到客户端        response.setContentType("application/octet-stream");        response.setHeader("Cache-Control","must-revalidate, post-check=0, pre-check=0");        response.setHeader("Pragma", "public");        //设置超时时间        response.setDateHeader("Expires",(System.currentTimeMillis() + 5000));        response.addHeader("Content-Disposition","attachment; filename=\""+ file.getName() + "\"");FileInputStream in = new FileInputStream(file);OutputStream out = response.getOutputStream();int len = 0;byte[] buffer = new byte[1024];while((len=in.read(buffer))!=-1){out.write(buffer, 0, len);out.flush();}out.close();in.close();}