public class FileUtil {
  public static void chmod(String path, int mode) throws Exception {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODE.LOLLIPOP) {
      try {
        Os.chmod(path,mode);
      } catch (Exception e) {
      // ignore
      }
    }

    File file = new File(path);
    String cmd = "chmod ";
    if (file.isDirectory()){
      cmd += " -R ";
    }

    // %o:整数类型(八进制)
    String cmode = String.format("%o", mode);
    Runtime.getRuntime().exec(cmd + cmode + " " + path).waitFor();

  }
}