python alimama.py 报错

[ChinaArJun]

Book-Pro:auto-login-alimama-master arjun$ python alimama.py
Traceback (most recent call last):
File "alimama.py", line 56, in
sp = Spider()
File "alimama.py", line 12, in init
self.web = webdriver.Chrome()
File "/usr/local/lib/python2.7/site-packages/selenium/webdriver/chrome/webdriver.py", line 73, in init
self.service.start()
File "/usr/local/lib/python2.7/site-packages/selenium/webdriver/common/service.py", line 83, in start
os.path.basename(self.path), self.start_error_message)
selenium.common.exceptions.WebDriverException: Message: 'chromedriver' executable needs to be in PATH. Please see https://sites.google.com/a/chromium.org/chromedriver/home