code: public static String[] scanFolderAsArray(String folder) {
          List<String> list = scanFolder(folder);
          String[] arrays = new String[list.size()];
          int i = 0;
          for (String item : list) {
              arrays[i++] = item;
          }
          return arrays;
      }
docs: 扫描文件夹下面所有文件
  
  @param folder 文件夹
  
  @return 文件路径列表