文档说我可以：
lxml can parse from a local file,an HTTP URL or an FTP URL. It also
auto-detects and reads gzip-compressed XML files (.gz).
(从“Parsers”下的http://lxml.de/parsing.html起)
但一个快速的实验似乎暗示：
Python 3.4.1 (v3.4.1:c0e311e010fc,May 18 2014,10:45:13) [MSC v.1600 64 bit (AMD64)] on win32
Type "help","copyright","credits" or "license" for more information.
>>> from lxml import etree
>>> parser = etree.HTMLParser()
>>> from urllib.request import urlopen
>>> with urlopen('https://pypi.python.org/simple') as f:
... tree = etree.parse(f,parser)
...
>>> tree2 = etree.parse('https://pypi.python.org/simple',parser)
Traceback (most recent call last):
File "<stdin>",line 1,in <module>
File "lxml.etree.pyx",line 3299,in lxml.etree.parse (src\lxml\lxml.etree.c:72655)
File "parser.pxi",line 1791,in lxml.etree._parseDocument (src\lxml\lxml.etree.c:106263)
File "parser.pxi",line 1817,in lxml.etree._parseDocumentFromURL (src\lxml\lxml.etree.c:106564)
File "parser.pxi",line 1721,in lxml.etree._parseDocFromFile (src\lxml\lxml.etree.c:105561)
File "parser.pxi",line 1122,in lxml.etree._BaseParser._parseDocFromFile (src\lxml\lxml.etree.c:100456)
File "parser.pxi",line 580,in lxml.etree._ParserContext._handleParseResultDoc (src\lxml\lxml.etree.c:94543)
File "parser.pxi",line 690,in lxml.etree._handleParseResult (src\lxml\lxml.etree.c:96003)
File "parser.pxi",line 618,in lxml.etree._raiseParseError (src\lxml\lxml.etree.c:95015)
OSError: Error reading file 'https://pypi.python.org/simple': Failed to load external entity "https://pypi.python.org/simple"
>>>
我可以使用urlopen方法,但文档似乎暗示传递URL在某种程度上更好.另外,如果文档不准确,我有点担心依赖lxml,特别是如果我开始需要做更复杂的事情.
从已知的URL解析带有lxml的HTML的正确方法是什么？我应该在哪里看到有记录的？
更新：如果我使用http网址而不是https网址,我会收到同样的错误.
解决方法
问题是lxml不支持HTTPS URL,而
http://pypi.python.org/simple重定向到HTTPS版本.
因此,对于任何安全的网站,您需要自己阅读URL：
from lxml import etree
from urllib.request import urlopen
parser = etree.HTMLParser()
with urlopen('https://pypi.python.org/simple') as f:
tree = etree.parse(f,parser)