Android应用程序里创建文件及改变权限

String dir = "/data/data/com.example.helloyude/files/";String fileName = "mac_address.txt";String macAddress = "xx:xx:xx:xx:xx";File destDir = new File(dir);if (!destDir.exists()) {destDir.mkdirs();}// 修改权限FileOutputStream fos;try {//方法1.增加其全局可读写权限fos = openFileOutput(fileName, MODE_WORLD_READABLE | MODE_WORLD_WRITEABLE);byte[] bytes = macAddress.getBytes();fos.write(bytes);fos.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}//方法2，直接更改文件权限Process p;int status = -1;try {p = Runtime.getRuntime().exec("chmod 777 " + dir + fileName);status = p.waitFor();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}if (status == 0) {                     Toast.makeText(this, "chmod succeed", Toast.LENGTH_LONG).show();            } else {                    Toast.makeText(this, "chmod failed", Toast.LENGTH_LONG).show();            }