Android 擷取root許可權 實現重啟

怎麼擷取root許可權，這是個問題。網上說用mk+uid能獲得，早之前我只會用cmd去擷取，而且還要安裝一個superuser前提還要是已經破解過的

代碼如下：(求大神賜教mk的方法)

 

Process process = null;
                        DataOutputStream os = null;
                        try {
                            process = Runtime.getRuntime().exec("su");
                            os = new DataOutputStream(process.getOutputStream());
                            os.writeBytes(" exit \n");
                            os.writeBytes(" exit \n");
                            os.flush();
                            process.waitFor();
                        } catch (Exception e) {
                        } finally {
                            try {
                                if (os != null) {
                                    os.close();
                                }
                                process.destroy();
                            } catch (Exception e) {
                            }
                        }//先擷取應用root Process process = null;
    DataOutputStream os = null;
    try {
     process = Runtime.getRuntime().exec("su");
     os = new DataOutputStream(process.getOutputStream());
     os.writeBytes(" reboot -p \n");//重啟代碼= = 我在cmd裡面su了之後還是不能關機，只能重啟。哎。
     os.flush();
     process.waitFor();
    } catch (Exception e) {
    } finally {
     try {
      if (os != null) {
       os.close();
      }
      process.destroy();
     } catch (Exception e) {
     }
    }

求大神賜教真正擷取root許可權。