获取目录内所有文件名字列表，可供下载等

public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  //定义一个存储文件名的集合list
  List<String> fileNames = new ArrayList<String>();
  //获得存储文件的绝对路径
  String path = request.getSession().getServletContext().getRealPath("/upload/");
  //创建文件对象
  File file = new File(path);
  if(file.isDirectory()){
   //获得目录下所有文件
   File[] files = file.listFiles();
   for(File fi : files){
    fileNames.add(fi.getName());
   }
  }
  request.setAttribute("downfiles", fileNames);
  request.getRequestDispatcher("/down.jsp").forward(request, response);
 }