public static void download(String path, HttpServletResponse response) {
  try {
    // path是指欲下载的文件的路径。
    File file = new File(path);
    // 取得文件名。
    String filename = file.getName();
    // 取得文件的后缀名。
    String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
    // 以流的形式下载文件。
    InputStream fis = new BufferedInputStream(new FileInputStream(path));
    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="
        + new String(filename.getBytes()));
    response.addHeader("Content-Length", "" + file.length());
    OutputStream toClient = new BufferedOutputStream(
        response.getOutputStream());
    response.setContentType("application/octet-stream");
    toClient.write(buffer);
    toClient.flush();
    toClient.close();
  } catch (IOException ex) {
    ex.printStackTrace();
  }
}