(1):第一种方法是在命令上加上-s USER_AGENT='Mozilla/5.0'
(2):第二种方法是修改scrapy的user-agent默认值
找到Python的:安装目录下的default_settings.py文件,
C:Program Files (x86)Anaconda2envsscrapyLibsite-packagesscrapysettingsdefault_settings.py
修改269行，USER_AGENT；
USER_AGENT = 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36'
(2):第在请求头部构造一个User Agent，如下所示：
1 def start_requests(self): 2 yield Request("http://www.baidu.com/", 3 headers={'User-Agent': "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36"})