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python--爬虫入门(八)体验HTMLParser解析网页,网页抓取解析整合练习

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python系列均基于python3.4环境 

  • 基本概念

  html.parser的核心是HTMLParser类。工作的流程是:当你feed给它一个类似HTML格式的字符串时,它会调用goahead方法向前迭代各个标签,并调用对应的parse_xxxx方法提取start_tag,tag,data,comment和end_tag等等标签信息和数据,然后调用对应的方法对这些抽取出来的内容进行处理。

技术分享 

  • 几个比较常用的:
handle_startendtag  #处理开始标签和结束标签
handle_starttag     #处理开始标签,比如<xx>
handle_endtag       #处理结束标签,比如</xx>或者<……/>
handle_charref      #处理特殊字符串,就是以&#开头的,一般是内码表示的字符
handle_entityref    #处理一些特殊字符,以&开头的,比如 &nbsp;
handle_data         #处理<xx>data</xx>中间的那些数据
handle_comment      #处理注释
handle_decl         #处理<!开头的,比如<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
handle_pi           #处理形如<?instruction>的

 

  @_@) 接下来,我们来体验下html.parser!!!

  • 下面这一段将是用来做测试数据的html代码段:
<head>
    <meta charset="utf-8"/>
    <title>找找看 - 博客园</title>
    <link rel="shortcut icon" href="/Content/Images/favicon.ico" type="image/x-icon"/>
    <meta content="技术搜索,IT搜索,程序搜索,代码搜索,程序员搜索引擎" name="keywords" />
    <meta content="面向程序员的专业搜索引擎。遇到技术问题怎么办,到博客园找找看..." name="description" />
    <link type="text/css" href="/Content/Style.css" rel="stylesheet" />
    <script src="http://common.cnblogs.com/script/jquery.js" type="text/javascript"></script>
    <script src="/Scripts/Common.js" type="text/javascript"></script>
    <script src="/Scripts/Home.js" type="text/javascript"></script>
</head>
  • 体验三个基本函数:
def handle_starttag(self, tag, attrs)  #处理开始标签,比如<xx>
def handle_data(self, data)            #处理<xx>data</xx>中间的那些数据
def handle_endtag(self, tag)           #处理结束标签,比如</xx>或者<……/>
  • 代码示例:(python3.4)
import html.parser as h

class MyHTMLParser(h.HTMLParser):

    a_t=False

    #处理开始标签,比如<xx>
    def handle_starttag(self, tag, attrs):
        print("开始一个标签:",tag)

        if str(tag).startswith("title"):
            self.a_t=True

        for attr in attrs:
            print("属性值:",attr)
       # print()

    #处理<xx>data</xx>中间的那些数据
    def handle_data(self, data):
        if self.a_t is True:
            print("得到的数据: ",data)

    #处理结束标签,比如</xx>或者<……/>
    def handle_endtag(self, tag):
        self.a_t=False
        print("结束一个标签:",tag)
        print()

p=MyHTMLParser()
mystr = ‘‘‘<head>
    <meta charset="utf-8"/>
    <title>找找看 - 博客园</title>
    <link rel="shortcut icon" href="/Content/Images/favicon.ico" type="image/x-icon"/>
    <meta content="技术搜索,IT搜索,程序搜索,代码搜索,程序员搜索引擎" name="keywords" />
    <meta content="面向程序员的专业搜索引擎。遇到技术问题怎么办,到博客园找找看..." name="description" />
    <link type="text/css" href="/Content/Style.css" rel="stylesheet" />
    <script src="http://common.cnblogs.com/script/jquery.js" type="text/javascript"></script>
    <script src="/Scripts/Common.js" type="text/javascript"></script>
    <script src="/Scripts/Home.js" type="text/javascript"></script>
</head>‘‘‘
p.feed(mystr)
p.close()
  • 运行结果:
技术分享
C:\Python34\python.exe E:/pythone_workspace/mydemo/spider/h2.py
开始一个标签: head
开始一个标签: meta
属性值: (charset, utf-8)
结束一个标签: meta

开始一个标签: title
得到的数据:  找找看 - 博客园
结束一个标签: title

开始一个标签: link
属性值: (rel, shortcut icon)
属性值: (href, /Content/Images/favicon.ico)
属性值: (type, image/x-icon)
结束一个标签: link

开始一个标签: meta
属性值: (content, 技术搜索,IT搜索,程序搜索,代码搜索,程序员搜索引擎)
属性值: (name, keywords)
结束一个标签: meta

开始一个标签: meta
属性值: (content, 面向程序员的专业搜索引擎。遇到技术问题怎么办,到博客园找找看...)
属性值: (name, description)
结束一个标签: meta

开始一个标签: link
属性值: (type, text/css)
属性值: (href, /Content/Style.css)
属性值: (rel, stylesheet)
结束一个标签: link

开始一个标签: script
属性值: (src, http://common.cnblogs.com/script/jquery.js)
属性值: (type, text/javascript)
结束一个标签: script

开始一个标签: script
属性值: (src, /Scripts/Common.js)
属性值: (type, text/javascript)
结束一个标签: script

开始一个标签: script
属性值: (src, /Scripts/Home.js)
属性值: (type, text/javascript)
结束一个标签: script

结束一个标签: head


Process finished with exit code 0
View Result

 


-------@_@? html.parser------------------------------------------------------------

提问:除了上面列出的比较常用的功能之外?还有什么别的功能呢?

--------------------------------------------------------------------------------------

 

了解下html.parser还有什么功能!!!

  • 代码如下:
import html.parser
help(html.parser)
  • 运行结果:
技术分享
C:\Python34\python.exe E:/pythone_workspace/mydemo/test.py
Help on module html.parser in html:

NAME
    html.parser - A parser for HTML and XHTML.

CLASSES
    _markupbase.ParserBase(builtins.object)
        HTMLParser
    
    class HTMLParser(_markupbase.ParserBase)
     |  Find tags and other markup and call handler functions.
     |  
     |  Usage:
     |      p = HTMLParser()
     |      p.feed(data)
     |      ...
     |      p.close()
     |  
     |  Start tags are handled by calling self.handle_starttag() or
     |  self.handle_startendtag(); end tags by self.handle_endtag().  The
     |  data between tags is passed from the parser to the derived class
     |  by calling self.handle_data() with the data as argument (the data
     |  may be split up in arbitrary chunks).  If convert_charrefs is
     |  True the character references are converted automatically to the
     |  corresponding Unicode character (and self.handle_data() is no
     |  longer split in chunks), otherwise they are passed by calling
     |  self.handle_entityref() or self.handle_charref() with the string
     |  containing respectively the named or numeric reference as the
     |  argument.
     |  
     |  Method resolution order:
     |      HTMLParser
     |      _markupbase.ParserBase
     |      builtins.object
     |  
     |  Methods defined here:
     |  
     |  __init__(self, strict=<object object at 0x00A50488>, *, convert_charrefs=<object object at 0x00A50488>)
     |      Initialize and reset this instance.
     |      
     |      If convert_charrefs is True (default: False), all character references
     |      are automatically converted to the corresponding Unicode characters.
     |      If strict is set to False (the default) the parser will parse invalid
     |      markup, otherwise it will raise an error.  Note that the strict mode
     |      and argument are deprecated.
     |  
     |  check_for_whole_start_tag(self, i)
     |      # Internal -- check to see if we have a complete starttag; return end
     |      # or -1 if incomplete.
     |  
     |  clear_cdata_mode(self)
     |  
     |  close(self)
     |      Handle any buffered data.
     |  
     |  error(self, message)
     |  
     |  feed(self, data)
     |      Feed data to the parser.
     |      
     |      Call this as often as you want, with as little or as much text
     |      as you want (may include \n).
     |  
     |  get_starttag_text(self)
     |      Return full source of start tag: <...>.
     |  
     |  goahead(self, end)
     |      # Internal -- handle data as far as reasonable.  May leave state
     |      # and data to be processed by a subsequent call.  If end is
     |      # true, force handling all data as if followed by EOF marker.
     |  
     |  handle_charref(self, name)
     |      # Overridable -- handle character reference
     |  
     |  handle_comment(self, data)
     |      # Overridable -- handle comment
     |  
     |  handle_data(self, data)
     |      # Overridable -- handle data
     |  
     |  handle_decl(self, decl)
     |      # Overridable -- handle declaration
     |  
     |  handle_endtag(self, tag)
     |      # Overridable -- handle end tag
     |  
     |  handle_entityref(self, name)
     |      # Overridable -- handle entity reference
     |  
     |  handle_pi(self, data)
     |      # Overridable -- handle processing instruction
     |  
     |  handle_startendtag(self, tag, attrs)
     |      # Overridable -- finish processing of start+end tag: <tag.../>
     |  
     |  handle_starttag(self, tag, attrs)
     |      # Overridable -- handle start tag
     |  
     |  parse_bogus_comment(self, i, report=1)
     |      # Internal -- parse bogus comment, return length or -1 if not terminated
     |      # see http://www.w3.org/TR/html5/tokenization.html#bogus-comment-state
     |  
     |  parse_endtag(self, i)
     |      # Internal -- parse endtag, return end or -1 if incomplete
     |  
     |  parse_html_declaration(self, i)
     |      # Internal -- parse html declarations, return length or -1 if not terminated
     |      # See w3.org/TR/html5/tokenization.html#markup-declaration-open-state
     |      # See also parse_declaration in _markupbase
     |  
     |  parse_pi(self, i)
     |      # Internal -- parse processing instr, return end or -1 if not terminated
     |  
     |  parse_starttag(self, i)
     |      # Internal -- handle starttag, return end or -1 if not terminated
     |  
     |  reset(self)
     |      Reset this instance.  Loses all unprocessed data.
     |  
     |  set_cdata_mode(self, elem)
     |  
     |  unescape(self, s)
     |      # Internal -- helper to remove special character quoting
     |  
     |  unknown_decl(self, data)
     |  
     |  ----------------------------------------------------------------------
     |  Data and other attributes defined here:
     |  
     |  CDATA_CONTENT_ELEMENTS = (script, style)
     |  
     |  ----------------------------------------------------------------------
     |  Methods inherited from _markupbase.ParserBase:
     |  
     |  getpos(self)
     |      Return current line number and offset.
     |  
     |  parse_comment(self, i, report=1)
     |      # Internal -- parse comment, return length or -1 if not terminated
     |  
     |  parse_declaration(self, i)
     |      # Internal -- parse declaration (for use by subclasses).
     |  
     |  parse_marked_section(self, i, report=1)
     |      # Internal -- parse a marked section
     |      # Override this to handle MS-word extension syntax <![if word]>content<![endif]>
     |  
     |  updatepos(self, i, j)
     |      # Internal -- update line number and offset.  This should be
     |      # called for each piece of data exactly once, in order -- in other
     |      # words the concatenation of all the input strings to this
     |      # function should be exactly the entire input.
     |  
     |  ----------------------------------------------------------------------
     |  Data descriptors inherited from _markupbase.ParserBase:
     |  
     |  __dict__
     |      dictionary for instance variables (if defined)
     |  
     |  __weakref__
     |      list of weak references to the object (if defined)

DATA
    __all__ = [HTMLParser]

FILE
    c:\python34\lib\html\parser.py



Process finished with exit code 0
View Result

 

 

---------@_@! 整合练习--------------------------------------------------------------

上一篇python--爬虫入门(七)urllib库初体验以及中文编码问题的探讨,提到抓取网页!

那么,我们将前面内容和上篇整合一下,练习练习

----------------------------------------------------------------------------------------

 

开始整合练习!!!

  •  新建package,命名为spider,新建两个.py文件。

技术分享

(1)HtmlParser.py代码如下:

import html.parser as h

class MyHTMLParser(h.HTMLParser):

    a_t=False

    #处理开始标签,比如<xx>
    def handle_starttag(self, tag, attrs):
        print("开始一个标签:",tag)

        if str(tag).startswith("title"):
            self.a_t=True

        for attr in attrs:
            print("属性值:",attr)
       # print()

    #处理<xx>data</xx>中间的那些数据
    def handle_data(self, data):
        if self.a_t is True:
            print("得到的数据: ",data)

    #处理结束标签,比如</xx>或者<……/>
    def handle_endtag(self, tag):
        self.a_t=False
        print("结束一个标签:",tag)
        print()

(2)Demo.py代码如下:

import urllib.request
import urllib.parse
import spider.HtmlParser

response=urllib.request.urlopen("http://zzk.cnblogs.com/b")
myStr=response.read().decode(UTF-8)
print("-----------网页源码-----------------")
print(myStr)
print("-----------开始解析网页-------------")
p=spider.HtmlParser.MyHTMLParser()
p.feed(myStr)
p.close()
  • 运行Demo.py,结果显示:
技术分享
C:\Python34\python.exe E:/pythone_workspace/mydemo/spider/Demo.py
-----------网页源码-----------------

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
    <title>找找看 - 博客园</title>    
    <link rel="shortcut icon" href="/Content/Images/favicon.ico" type="image/x-icon"/>
    <meta content="技术搜索,IT搜索,程序搜索,代码搜索,程序员搜索引擎" name="keywords" />
    <meta content="面向程序员的专业搜索引擎。遇到技术问题怎么办,到博客园找找看..." name="description" />
    <link type="text/css" href="/Content/Style.css" rel="stylesheet" />
    <script src="http://common.cnblogs.com/script/jquery.js" type="text/javascript"></script>
    <script src="/Scripts/Common.js" type="text/javascript"></script>
    <script src="/Scripts/Home.js" type="text/javascript"></script>
</head>
<body>
    <div class="top">
        
        <div class="top_tabs">
            <a href="http://www.cnblogs.com">« 博客园首页 </a>
        </div>
        <div id="span_userinfo" class="top_links">
        </div>
    </div>
    <div style="clear: both">
    </div>
    <center>
        <div id="main">
            <div class="logo_index">
                <a href="http://zzk.cnblogs.com">
                    <img alt="找找看logo" src="/images/logo.gif" /></a>
            </div>
            <div class="index_sozone">
                <div class="index_tab">
                    <a href="/n" onclick="return  channelSwitch(&#39;n&#39;);">新闻</a>
<a class="tab_selected" href="/b" onclick="return  channelSwitch(&#39;b&#39;);">博客</a>                    <a href="/k" onclick="return  channelSwitch(&#39;k&#39;);">知识库</a>
                    <a href="/q" onclick="return  channelSwitch(&#39;q&#39;);">博问</a>
                </div>
                <div class="search_block">
                    <div class="index_btn">
                        <input type="button" class="btn_so_index" onclick="Search();" value="&nbsp;找一下&nbsp;" />
                        <span class="help_link"><a target="_blank" href="/help">帮助</a></span>
                    </div>
                    <input type="text" onkeydown="searchEnter(event);" class="input_index" name="w" id="w" />
                </div>
            </div>
        </div>
        <div class="footer">
            &copy;2004-2016 <a href="http://www.cnblogs.com">博客园</a>
        </div>
    </center>
</body>
</html>

-----------开始解析网页-------------
开始一个标签: html
开始一个标签: head
开始一个标签: meta
属性值: (charset, utf-8)
结束一个标签: meta

开始一个标签: title
得到的数据:  找找看 - 博客园
结束一个标签: title

开始一个标签: link
属性值: (rel, shortcut icon)
属性值: (href, /Content/Images/favicon.ico)
属性值: (type, image/x-icon)
结束一个标签: link

开始一个标签: meta
属性值: (content, 技术搜索,IT搜索,程序搜索,代码搜索,程序员搜索引擎)
属性值: (name, keywords)
结束一个标签: meta

开始一个标签: meta
属性值: (content, 面向程序员的专业搜索引擎。遇到技术问题怎么办,到博客园找找看...)
属性值: (name, description)
结束一个标签: meta

开始一个标签: link
属性值: (type, text/css)
属性值: (href, /Content/Style.css)
属性值: (rel, stylesheet)
结束一个标签: link

开始一个标签: script
属性值: (src, http://common.cnblogs.com/script/jquery.js)
属性值: (type, text/javascript)
结束一个标签: script

开始一个标签: script
属性值: (src, /Scripts/Common.js)
属性值: (type, text/javascript)
结束一个标签: script

开始一个标签: script
属性值: (src, /Scripts/Home.js)
属性值: (type, text/javascript)
结束一个标签: script

结束一个标签: head

开始一个标签: body
开始一个标签: div
属性值: (class, top)
开始一个标签: div
属性值: (class, top_tabs)
开始一个标签: a
属性值: (href, http://www.cnblogs.com)
结束一个标签: a

结束一个标签: div

开始一个标签: div
属性值: (id, span_userinfo)
属性值: (class, top_links)
结束一个标签: div

结束一个标签: div

开始一个标签: div
属性值: (style, clear: both)
结束一个标签: div

开始一个标签: center
开始一个标签: div
属性值: (id, main)
开始一个标签: div
属性值: (class, logo_index)
开始一个标签: a
属性值: (href, http://zzk.cnblogs.com)
开始一个标签: img
属性值: (alt, 找找看logo)
属性值: (src, /images/logo.gif)
结束一个标签: img

结束一个标签: a

结束一个标签: div

开始一个标签: div
属性值: (class, index_sozone)
开始一个标签: div
属性值: (class, index_tab)
开始一个标签: a
属性值: (href, /n)
属性值: (onclick, "return  channelSwitch(‘n‘);")
结束一个标签: a

开始一个标签: a
属性值: (class, tab_selected)
属性值: (href, /b)
属性值: (onclick, "return  channelSwitch(‘b‘);")
结束一个标签: a

开始一个标签: a
属性值: (href, /k)
属性值: (onclick, "return  channelSwitch(‘k‘);")
结束一个标签: a

开始一个标签: a
属性值: (href, /q)
属性值: (onclick, "return  channelSwitch(‘q‘);")
结束一个标签: a

结束一个标签: div

开始一个标签: div
属性值: (class, search_block)
开始一个标签: div
属性值: (class, index_btn)
开始一个标签: input
属性值: (type, button)
属性值: (class, btn_so_index)
属性值: (onclick, Search();)
属性值: (value, \xa0找一下\xa0)
结束一个标签: input

开始一个标签: span
属性值: (class, help_link)
开始一个标签: a
属性值: (target, _blank)
属性值: (href, /help)
结束一个标签: a

结束一个标签: span

结束一个标签: div

开始一个标签: input
属性值: (type, text)
属性值: (onkeydown, searchEnter(event);)
属性值: (class, input_index)
属性值: (name, w)
属性值: (id, w)
结束一个标签: input

结束一个标签: div

结束一个标签: div

结束一个标签: div

开始一个标签: div
属性值: (class, footer)
开始一个标签: a
属性值: (href, http://www.cnblogs.com)
结束一个标签: a

结束一个标签: div

结束一个标签: center

结束一个标签: body

结束一个标签: html


Process finished with exit code 0
View Result

 

(@_@)Y,本篇分享到这里!待续~

 

python--爬虫入门(八)体验HTMLParser解析网页,网页抓取解析整合练习

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原文地址:http://www.cnblogs.com/lmei/p/5338026.html

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