bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need to install a parser library?

bs4解析网页时报错：bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need to install a parser library?

原因：不可以使用 BeautifulSoup(html,'html_parser')

解决办法：

1.安装 pip install lxml

2.将BeautifulSoup(html,'html_parser') 改为BeautifulSoup(html,'lxml')