UserAgent判断浏览器类型或爬虫类型
### 浏览器
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- IE
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3)
- Chrome
Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36
Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.96 Mobile Safari/537.36
- Firefox
Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0
### 爬虫
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- Googlebot
Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
- Baiduspider
Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)
- AhrefsBot
Mozilla/5.0 (compatible; AhrefsBot/5.2; +http://ahrefs.com/robot/)
- 阿里云盾
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;Alibaba.Security.Heimdall.5448812)