HTMLParser in python

You can know form the name that the HTMLParser is something used to parse
HTML files.  In python, there are two HTMLParsers. One is the HTMLParser
class defined in htmllib module—— htmllib.HTMLParser, the other one is
HTMLParser class defined in HTMLParser module. Let`s see them separately.

htmllib.HTMLParser

This is deprecated since python2.6. The htmllib is removed in python3. But
still, there is something you could know about it. This parser is not
directly concerned with I/O — it must be provided with input in string form via
a method, and makes calls to methods of a “formatter” object in order to produce
output. So you need to do it in below way for instantiation purpose.

>>> from cStringIO import StringIO

>>> from formatter import DumbWriter, AbstractFormatter

>>> from htmllib import HTMLParser

>>> parser = HTMLParser(AbstractFormatter(DumbWriter(StringIO())))

>>>

It is very annoying. All you want to do is parsing a html file, but now you
have to know a lot other things like format, I/O stream etc.

HTMLParser.HTMLParser

In python3 this module is renamed to html.parser. This module does the
samething as htmllib.HTMLParser. The good thing is you do not to import modules
like formatter and cStringIO.  For more information you can go to this URL
:

https://docs.python.org/2.7/library/htmlparser.html?highlight=htmlparser#HTMLParser

Here is some briefly introduction for this module.

See below for a sample code while using this module. You will notice that you
do not need to use formater class or I/O string class.

?

Another case here, in the htmllib.HTMLParser, there was two functions as
below,

HTMLParser.anchor_bgn(href, name, type)

This method is called at the start of an anchor region. The arguments correspond to the attributes of the <A> tag with the same names. The default implementation maintains a list of hyperlinks (defined by the HREF attribute for <A> tags) within the document. The list of hyperlinks is available as the data attribute anchorlist.

HTMLParser.anchor_end()

This method is called at the end of an anchor region. The default implementation adds a textual footnote marker using an index into the list of hyperlinks created by anchor_bgn().

With these two funcitons, htmllib.HTMLParser can easily retrive url links
from a html file. For example:

>>> from urlparse import urlparse

>>> from formatter import DumbWriter, AbstractFormatter

>>> from cStringIO import StringIO

>>> from htmllib import HTMLParser

>>>

>>> def parseAndGetLinks():

...     parser = HTMLParser(AbstractFormatter(DumbWriter(StringIO())))

...     parser.feed(open(file).read())

...     parser.close()

...     return parser.anchorlist

...

>>> file=‘/tmp/a.ttt‘

>>> parseAndGetLinks()

[‘http://www.baidu.com/gaoji/preferences.html‘, ‘/‘, ‘https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘https://passport.baidu.com/v2/?reg&regType=1&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘/‘, ‘http://news.baidu.com/ns?cl=2&rn=20&tn=news&word=‘, ‘http://tieba.baidu.com/f?kw=&fr=wwwt‘, ‘http://zhidao.baidu.com/q?ct=17&pn=0&tn=ikaslist&rn=10&word=&fr=wwwt‘, ‘http://music.baidu.com/search?fr=ps&key=‘, ‘http://image.baidu.com/i?tn=baiduimage&ct=201326592&lm=-1&cl=2&nc=1&word=‘, ‘http://v.baidu.com/v?ct=301989888&rn=20&pn=0&db=0&s=25&word=‘, ‘http://map.baidu.com/m?word=&fr=ps01000‘, ‘http://wenku.baidu.com/search?word=&lm=0&od=0‘, ‘http://www.baidu.com/more/‘, ‘javascript:;‘, ‘javascript:;‘, ‘javascript:;‘, ‘http://shouji.baidu.com/baidusearch/mobisearch.html?ref=pcjg&from=1000139w‘, ‘http://www.baidu.com/gaoji/preferences.html‘, ‘https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘https://passport.baidu.com/v2/?reg&regType=1&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘http://news.baidu.com‘, ‘http://tieba.baidu.com‘, ‘http://zhidao.baidu.com‘, ‘http://music.baidu.com‘, ‘http://image.baidu.com‘, ‘http://v.baidu.com‘, ‘http://map.baidu.com‘, ‘javascript:;‘, ‘javascript:;‘, ‘javascript:;‘, ‘http://baike.baidu.com‘, ‘http://wenku.baidu.com‘, ‘http://www.hao123.com‘, ‘http://www.baidu.com/more/‘, ‘/‘, ‘http://www.baidu.com/cache/sethelp/index.html‘, ‘http://e.baidu.com/?refer=888‘, ‘http://top.baidu.com‘, ‘http://home.baidu.com‘, ‘http://ir.baidu.com‘, ‘/duty/‘]

But in HTMLParser.HTMLParser, we do not have these two functions. Does not
matter, we can define our own.

 1 >>> from HTMLParser import HTMLParser

 2 >>> class myHtmlParser(HTMLParser):

 3 ...     def __init__(self):

 4 ...             HTMLParser.__init__(self)

 5 ...             self.anchorlist=[]

 6 ...     def handle_starttag(self, tag, attrs):

 7 ...                     if tag==‘a‘ or tag==‘A‘:

 8 ...                             for t in attrs :

 9 ...                                     if t[0] == ‘href‘ or t[0]==‘HREF‘:

10 ...                                             self.anchorlist.append(t[1])

11 ...

12 >>> file=‘/tmp/a.ttt‘

13 >>> parser=myHtmlParser()

14 >>> parser.feed(open(file).read())

15 >>> parser.anchorlist

16 [‘http://www.baidu.com/gaoji/preferences.html‘, ‘/‘, ‘https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘https://passport.baidu.com/v2/?reg&regType=1&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘/‘, ‘http://news.baidu.com/ns?cl=2&rn=20&tn=news&word=‘, ‘http://tieba.baidu.com/f?kw=&fr=wwwt‘, ‘http://zhidao.baidu.com/q?ct=17&pn=0&tn=ikaslist&rn=10&word=&fr=wwwt‘, ‘http://music.baidu.com/search?fr=ps&key=‘, ‘http://image.baidu.com/i?tn=baiduimage&ct=201326592&lm=-1&cl=2&nc=1&word=‘, ‘http://v.baidu.com/v?ct=301989888&rn=20&pn=0&db=0&s=25&word=‘, ‘http://map.baidu.com/m?word=&fr=ps01000‘, ‘http://wenku.baidu.com/search?word=&lm=0&od=0‘, ‘http://www.baidu.com/more/‘, ‘javascript:;‘, ‘javascript:;‘, ‘javascript:;‘, ‘http://shouji.baidu.com/baidusearch/mobisearch.html?ref=pcjg&from=1000139w‘, ‘http://www.baidu.com/gaoji/preferences.html‘, ‘https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘https://passport.baidu.com/v2/?reg&regType=1&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F‘, ‘http://news.baidu.com‘, ‘http://tieba.baidu.com‘, ‘http://zhidao.baidu.com‘, ‘http://music.baidu.com‘, ‘http://image.baidu.com‘, ‘http://v.baidu.com‘, ‘http://map.baidu.com‘, ‘javascript:;‘, ‘javascript:;‘, ‘javascript:;‘, ‘http://baike.baidu.com‘, ‘http://wenku.baidu.com‘, ‘http://www.hao123.com‘, ‘http://www.baidu.com/more/‘, ‘/‘, ‘http://www.baidu.com/cache/sethelp/index.html‘, ‘http://e.baidu.com/?refer=888‘, ‘http://top.baidu.com‘, ‘http://home.baidu.com‘, ‘http://ir.baidu.com‘, ‘/duty/‘]

17 >>>

We look into the second code.

line 3 to line 5 overwrite the __init__ method. The key for this overwriten
is that add an new attribute - anchorlist to our instance.

line 6 to line 10 overwrite the handle_starttag method. First it use if to
check what the tag is. If it is ‘a‘ or ‘A‘,  then use for loop to check its
attribute. Retrieve the href attribute and put the value into the
anchorlist.

Then done.