def start(self):  """  Starts the Service.  :Exceptions:   - WebDriverException : Raised either when it can't start the service   or when it can't connect to the service  """  try:   cmd = [self.path]   cmd.extend(self.command_line_args())   if 'win32' in str(sys.platform).lower(): ### 這里判斷是否是windows平臺(tái)    ### 在windows平臺(tái)上就隱藏窗口    startupinfo = subprocess.STARTUPINFO()    startupinfo.dwFlags = subprocess.CREATE_NEW_CONSOLE | subprocess.STARTF_USESHOWWINDOW    startupinfo.wShowWindow = subprocess.SW_HIDE   else:    startupinfo = None   self.process = subprocess.Popen(cmd, env=self.env,           close_fds=platform.system() != 'Windows',           stdout=self.log_file, stderr=self.log_file,startupinfo=startupinfo) ### 啟動(dòng)驅(qū)動(dòng)   self.PID = self.process.pid ### 將cmd窗口的進(jìn)程pid 保留 因?yàn)?窗口被隱藏了 所以在后續(xù)程序中必須考慮主控進(jìn)程結(jié)束的時(shí)候必須結(jié)束掉 驅(qū)動(dòng)cmd窗口進(jìn)程  except TypeError:   raise  except OSError as err:   if err.errno == errno.ENOENT:    raise WebDriverException(     "'%s' executable needs to be in PATH. %s" % (      os.path.basename(self.path), self.start_error_message)    )   elif err.errno == errno.EACCES:    raise WebDriverException(     "'%s' executable may have wrong permissions. %s" % (      os.path.basename(self.path), self.start_error_message)    )   else:    raise  except Exception as e:   raise WebDriverException(    "The executable %s needs to be available in the path. %s/n%s" %    (os.path.basename(self.path), self.start_error_message, str(e)))  count = 0  while True:   self.assert_process_still_running()   if self.is_connectable():    break   count += 1   time.sleep(1)   if count == 30:    raise WebDriverException("Can not connect to the Service %s" % self.path)