Python crawler--The BeautifulSoup of several methods of parsing web pages

Source: Internet
Author: User
Tags xml parser

I. Parser overview

Soup=beautifulsoup (Response.body)

When the page is parsed, the parser is not specified, and the default parser "Html.parser" is used in Python.

What is a parser? BeautifulSoup's job is to interpret and classify HTML tags, and different parsers will interpret the same HTML tags differently.

An example of an official document:

BeautifulSoup ("<a></p>", "lxml") # 
BeautifulSoup ("<a></p>", "Html5lib") # 
BeautifulSoup ("<a></p>", "Html.parser") # <a></a>

The "lxml" and "html5lib" parsers are frequently mentioned in the official documentation because the default "Html.parser" Auto-complete label is poorly functioning and often has problems.

Second, use BeautifulSoup crawl news website news headlines.

ImportRequests fromBs4ImportBeautifulsouplink="http://tuijian.hao123.com/finance"Headers= {'user-agent':'mozilla/5.0 (Windows; U Windows NT 6.1; En-us; rv:1.9.1.6) gecko/20091201 firefox/3.5.6'}r= Requests.get (link, headers=headers) Soup= BeautifulSoup (R.text,"Html.parser") First_title= Soup.find ("Div", class_="Box-text"). TextPrint("the title of the first article is:", First_title) title_list= Soup.find_all ("Div", class_="Box-text") forIinchRange (len (title_list)): Title=Title_list[i].text.strip ()Print('the title of article%s is:%s'% (i+1, title))

Find_all Find all results, the result is a list. Use a loop to list the headings.

Parser How to use Advantages Disadvantage
Python Standard library BeautifulSoup (markup, "Html.parser")
  • Python's built-in standard library
  • Moderate execution speed
  • Strong document Tolerance
  • Poor document tolerance in versions prior to Python 2.7.3 or 3.2.2
lxml HTML Parser BeautifulSoup (markup, "lxml")
  • Fast speed
  • Strong document Tolerance
  • Need to install the C language Library
lxml XML Parser BeautifulSoup (markup, ["lxml", "xml"]) BeautifulSoup (markup, "XML")
  • Fast speed
  • The only parser that supports XML
  • Need to install the C language Library
Html5lib BeautifulSoup (markup, "Html5lib")
  • Best-in-tolerance
  • Parsing documents in a browser way
  • Generate documents in HTML5 format
  • Slow speed

Python crawler--BeautifulSoup of several methods of parsing Web pages

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