java 使用response导出文件

try {

        // path是指欲下载的文件的路径。
        File file = new File(pathName);
        // 以流的形式下载文件。
        InputStream fis = new BufferedInputStream(new FileInputStream(pathName));
        byte[] buffer = new byte[fis.available()];
        fis.read(buffer);
        fis.close();
        // 清空response
        response.reset();
        // 设置response的Header
        response.addHeader("Content-Disposition", "attachment;filename=" + "register.bin");
        response.addHeader("Content-Length", "" + file.length());
        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
        response.setContentType("application/octet-stream");
        response.addHeader("Access-Control-Allow-Origin", "*");
        response.addHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
        response.addHeader("Access-Control-Allow-Headers", "Content-Type");
        toClient.write(buffer);
        toClient.flush();
        toClient.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }