python - 如何使用 pythonw 运行 Selenium Webdriver？

Question

我正在尝试通过 Windows 中的 GUI 应用程序在 Selenium 脚本中打开 Firefox 浏览器。它在使用 python.exe runw.py 运行时很好，但是当我使用 pythonw.exe runw.py 运行它时，浏览器无法启动。相反，它抛出这个异常:

Traceback (most recent call last):
  File "bin\runw.py", line 215, in process_instance
    instance.setup()
  File "bin\mixin.py", line 181, in setup
    self.browser = self.get_firefox_browser()
  File "bin\mixin.py", line 166, in get_firefox_browser
    firefox_binary=binary, firefox_profile=profile)
  File "C:\myvirtualenv\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 59, in __init__
    self.binary, timeout),
  File "C:\myvirtualenv\lib\site-packages\selenium\webdriver\firefox\extension_connection.py", line 47, in __init__
    self.binary.launch_browser(self.profile)
  File "C:\myvirtualenv\lib\site-packages\selenium\webdriver\firefox\firefox_binary.py", line 60, in launch_browser
    self._start_from_profile_path(self.profile.path)
  File "C:\myvirtualenv\lib\site-packages\selenium\webdriver\firefox\firefox_binary.py", line 83, in _start_from_profile_path
    env=self._firefox_env).communicate()
  File "C:\Python27\Lib\subprocess.py", line 702, in __init__
    errread, errwrite), to_close = self._get_handles(stdin, stdout, stderr)
  File "C:\Python27\Lib\subprocess.py", line 833, in _get_handles
    p2cread = self._make_inheritable(p2cread)
  File "C:\Python27\Lib\subprocess.py", line 884, in _make_inheritable
    _subprocess.DUPLICATE_SAME_ACCESS)
WindowsError: [Error 6] The handle is invalid

问题当然在于没有 stdin 或 stdout(我不确定)，因为它在这一行失败(firefox_binary.py):

def _start_from_profile_path(self, path):
    ...
    Popen(command, stdout=self._log_file, stderr=STDOUT,
          env=self._firefox_env).communicate()
    command[1] = '-foreground'
    self.process = Popen(
        command, stdout=self._log_file, stderr=STDOUT,
        env=self._firefox_env)

我试过在运行浏览器之前用输出文件覆盖 syd.stdout，但没有成功:

sys.stdout = sys.stderr = open('log.txt', 'a+')

我正在运行 Python2.7 和 Selenium 2.40。 Selenium 如何与 pythonw 一起运行？

Answer 1

正如@falsetru 所说，subprocess 正在尝试使用文件描述符0。如果所有句柄都有效(或者如果它们都是None)，并且 pythonw 是一个 Windows 进程并且不没有，我被迫子类化 FirefoxBinary 以使用 nul 句柄:

class WindowsFirefoxBinary(FirefoxBinary):

    def _start_from_profile_path(self, path):
        self._firefox_env["XRE_PROFILE_PATH"] = path

        if platform.system().lower() == 'linux':
            self._modify_link_library_path()
        command = [self._start_cmd, "-silent"]
        if self.command_line is not None:
            for cli in self.command_line:
                command.append(cli)

        # Added stdin argument:
        nul = open(os.devnull, 'w+')
        Popen(command, stdin=nul, stdout=self._log_file or nul, stderr=STDOUT,
              env=self._firefox_env).communicate()
        command[1] = '-foreground'
        self.process = Popen(
            command, stdin=nul, stdout=self._log_file or nul, stderr=STDOUT,
            env=self._firefox_env)

这样我可以在创建 WebDriver 实例时使用我自己的二进制文件:

binary = WindowsFirefoxBinary()
browser = webdriver.Firefox(firefox_binary=binary)

这可能是 Selenium 与 Python for Windows 的错误或不兼容。