python FileNotFoundError: [WinError 2] 系统找不到指定的文件。

Traceback (most recent call last):
  File "C:\_____Soft______python3.6libsite-packagesseleniumwebdrivercommon
service.py", line 76, in start
    stdin=PIPE)
  File "C:\_____Soft______python3.6libsubprocess.py", line 709, in __init__
    restore_signals, start_new_session)
  File "C:\_____Soft______python3.6libsubprocess.py", line 997, in _execute_c
hild
    startupinfo)
FileNotFoundError: [WinError 2] 系统找不到指定的文件。

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "alimama.py", line 76, in <module>
    sp = Spider()
  File "alimama.py", line 11, in __init__
    self.web = webdriver.Chrome()
  File "C:\_____Soft______python3.6libsite-packagesseleniumwebdriverchrome
webdriver.py", line 68, in __init__
    self.service.start()
  File "C:\_____Soft______python3.6libsite-packagesseleniumwebdrivercommon
service.py", line 83, in start
    os.path.basename(self.path), self.start_error_message)
selenium.common.exceptions.WebDriverException: Message: 'chromedriver' executabl
e needs to be in PATH. Please see https://sites.google.com/a/chromium.org/chrome
driver/home

 1、首先需要下载浏览器驱动
2、即便是firefox，在version>47时，也是需要安装firefox的浏览器驱动
3、浏览器驱动需要放在python安装目录
4、系统环境变量，path需要加入浏览器驱动地址

修改subprocess.py 文件

    def __init__(self, args, bufsize=-1, executable=None,
                 stdin=None, stdout=None, stderr=None,shell=true,  这里添加
                 preexec_fn=None, close_fds=_PLATFORM_DEFAULT_CLOSE_FDS,
                 shell=False, cwd=None, env=None, universal_newlines=False,
                 startupinfo=None, creationflags=0,
                 restore_signals=True, start_new_session=False,
                 pass_fds=(), *, encoding=None, errors=None):