如何处理lxml中的编码以正确解析html-string

Question

我有一个xml文件。请下载并保存为blog.xml。这是我在Google-blogger中的文件列表，我写了一些代码来解析它，lxml有一些问题。

code1:

from stripogram import html2text
import feedparser
d = feedparser.parse('blog.xml')
for num,entry in enumerate(d.entries):
    string=entry.content[0]['value'].encode("utf-8")
    print   html2text(string)

使用code1得到正确的结果。

code2:

import lxml.html
import feedparser
d = feedparser.parse('blog.xml')
for num,entry in enumerate(d.entries):
    string=entry.content[0]['value'] 
    myhtml=lxml.html.document_fromstring(string)
    print  myhtml.text_content()

使用code2得到错误的输出。

Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
  File "/usr/lib/python2.7/dist-packages/lxml/html/__init__.py", line 532, in document_fromstring
    value = etree.fromstring(html, parser, **kw)
  File "lxml.etree.pyx", line 2754, in lxml.etree.fromstring (src/lxml/lxml.etree.c:54631)
  File "parser.pxi", line 1569, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:82659)
 ValueError: Unicode strings with encoding declaration are not supported.

code3:

import lxml.html
import feedparser
d = feedparser.parse('blog.xml')
for num,entry in enumerate(d.entries):
    string=entry.content[0]['value'].encode("utf-8") 
    myhtml=lxml.html.document_fromstring(string)
    print  myhtml.text_content()

使用code3得到错误的输出。

 Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
  File "/usr/lib/python2.7/dist-packages/lxml/html/__init__.py", line 532, in document_fromstring
    value = etree.fromstring(html, parser, **kw)
  File "lxml.etree.pyx", line 2754, in lxml.etree.fromstring (src/lxml/lxml.etree.c:54631)
  File "parser.pxi", line 1578, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:82748)
  File "parser.pxi", line 1457, in lxml.etree._parseDoc (src/lxml/lxml.etree.c:81546)
  File "parser.pxi", line 965, in lxml.etree._BaseParser._parseDoc (src/lxml/lxml.etree.c:78216)
  File "parser.pxi", line 569, in lxml.etree._ParserContext._handleParseResultDoc (src/lxml/lxml.etree.c:74472)
  File "parser.pxi", line 650, in lxml.etree._handleParseResult (src/lxml/lxml.etree.c:75363)
  File "parser.pxi", line 599, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:74827)
 lxml.etree.XMLSyntaxError: line 1395: Tag b:include invalid

如何处理编码在lxml解析html字符串正确?

Answer 1

lxml中有一个错误。检查此代码的输出:

import lxml.html
import feedparser
def test():
    try:
        lxml.html.document_fromstring('')
    except Exception as e:
        print e
d = feedparser.parse('blog.xml')
e = d.entries[0].content[0]['value'].encode('utf-8')
test() # XMLSyntaxError: None
lxml.html.document_fromstring(e)
test() # XMLSyntaxError: line 1407: Tag b:include invalid

所以这个错误是令人困惑的，解析失败的真正原因是你传递了空字符串给document_fromstring。

试试这个代码:

import lxml.html
import feedparser
d = feedparser.parse('blog.xml')
for num,entry in enumerate(d.entries):
    string=entry.content[0]['value'].encode("utf-8") 
    if not string:
        continue
    myhtml=lxml.html.document_fromstring(string)
    print  myhtml.text_content()

Answer 2

您可以自己创建一个解析器，而不是使用document_fromstring:

from cStringIO import StringIO
from lxml import etree
for num, entry in enumerate(d.entries):
    text = entry.content[0]['value'].encode('utf8')
    parser = etree.HTMLParser()
    tree   = etree.parse(StringIO(text), parser)
    print  ''.join(tree.xpath('.//text()'))

对于Blogger.com的Atom提要导出，这可以打印.content[0].value条目的文本内容。