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Python爬虫基础之lxml
一、Python lxml的基本应用
1 <html> 2 <head> 3 <title> 4 The Dormouse‘s story 5 </title> 6 </head> 7 <body> 8 <p class="title"> 9 <b>10 The Dormouse‘s story11 </b>12 </p>13 <p class="story">14 Once upon a time there were three little sisters; and their names were15 <a class="sister" href="http://example.com/elsie" id="link1">16 Elsie17 </a>18 ,19 <a class="sister" href="http://example.com/lacie" id="link2">20 Lacie21 </a>22 and23 <a class="sister" href="http://example.com/tillie" id="link3">24 Tillie25 </a>26 ; and they lived at the bottom of a well.27 </p>28 <p class="story">29 ...30 </p>31 </body>32 </html>
1.使用lxml.etree和lxml.cssselect解析html源码
1 from lxml import etree, cssselect 2 from cssselect import GenericTranslator, SelectorError 3 4 parser = etree.HTMLParser(remove_blank_text=True) 5 document = etree.fromstring(html_doc, parser) 6 7 # 使用CSS选择器 8 sel = cssselect.CSSSelector(‘p a‘) 9 results_sel_href = http://www.mamicode.com/[e.get(‘href‘) for e in sel(document)] # 打印a标签的href属性10 results_sel_text = [e.text for e in sel(document)] # 打印<a></a>之间的文本11 print(results_sel_href)12 print(results_sel_text)13 14 # 使用CSS样式15 results_css = [e.get(‘href‘) for e in document.cssselect(‘p a‘)]16 print(results_css)17 18 19 # 使用xpath20 try:21 expression = GenericTranslator().css_to_xpath(‘p a‘)22 print(expression)23 except SelectorError:24 print(‘Invalid selector.‘)25 26 results_xpath = [e.get(‘href‘) for e in document.xpath(expression)] # document.xpath(‘//a‘)27 print(results_xpath)
2.cleaning up html
使用html清理器，可以移除一些嵌入的脚本、标签、CSS样式等html元素，这样可以提高搜索效率。
1 # cleaning up html 2 # 1.不使用Cleaner 3 from lxml.html.clean import Cleaner 4 html_after_clean = clean_html(html_doc) 5 print(html_after_clean) 6 # <div> 7 # The Dormouse‘s story 8 # <body> 9 # <p class="title">10 # <b>11 # The Dormouse‘s story12 # </b>13 # </p>14 # <p class="story">15 # Once upon a time there were three little sisters; and their names were16 # <a class="sister" href="http://example.com/elsie" id="link1">17 # Elsie18 # </a>19 # ,20 # <a class="sister" href="http://example.com/lacie" id="link2">21 # Lacie22 # </a>23 # and24 # <a class="sister" href="http://example.com/tillie" id="link3">25 # Tillie26 # </a>27 # ; and they lived at the bottom of a well.28 # </p>29 # <p class="story">30 # ...31 # </p>32 # </body>33 # </div>34 35 # 2.使用Cleaner36 cleaner = Cleaner(style=True, links=True, add_nofollow=True, page_structure=False, safe_attrs_only=False)37 html_with_cleaner = cleaner.clean_html(html_doc)38 print(html_with_cleaner)39 # <html>40 # <head>41 # <title>42 # The Dormouse‘s story43 # </title>44 # </head>45 # <body>46 # <p class="title">47 # <b>48 # The Dormouse‘s story49 # </b>50 # </p>51 # <p class="story">52 # Once upon a time there were three little sisters; and their names were53 # <a class="sister" href="http://example.com/elsie" id="link1">54 # Elsie55 # </a>56 # ,57 # <a class="sister" href="http://example.com/lacie" id="link2">58 # Lacie59 # </a>60 # and61 # <a class="sister" href="http://example.com/tillie" id="link3">62 # Tillie63 # </a>64 # ; and they lived at the bottom of a well.65 # </p>66 # <p class="story">67 # ...68 # </p>69 # </body>70 # </html>
二、Python lxml的实际应用
1.解析网易云音乐html源码
这是网易云音乐华语歌曲的分类链接http://music.163.com/#/discover/playlist/?order=hot&cat=华语&limit=35&offset=0，打开Chrome F12的Elements查看到页面源码，我们发现每页的歌单都在一个iframe浮窗上面，每首单曲的信息构成一个li标签，包含歌单图片、
歌单链接、歌单名称等。
1 <ul class="m-cvrlst f-cb" id="m-pl-container"> 2 <li> 3 <div class="u-cover u-cover-1"> 4 <img class="j-flag" src="http://p1.music.126.net/FGe-rVrHlBTbnOvhMR99PQ==/109951162989189558.jpg?param=140y140" /> 5 <a title="【说唱】留住你一面，画在我心间" href="/playlist?id=832790627" class="msk"></a> 6 <div class="bottom"> 7 <a class="icon-play f-fr" title="播放" href="javascript:;" data-res-type="13" data-res-id="832790627" data-res-action="play"></a> 8 <span class="icon-headset"></span> 9 <span class="nb">1615</span> 10 </div> 11 </div> <p class="dec"> <a title="【说唱】留住你一面，画在我心间" href="/playlist?id=832790627" class="tit f-thide s-fc0">【说唱】留住你一面，画在我心间</a> </p> <p><span class="s-fc4">by</span> <a title="JediMindTricks" href="/user/home?id=17647877" class="nm nm-icn f-thide s-fc3">JediMindTricks</a> <sup class="u-icn u-icn-84 "></sup> </p> </li> 12 <li> 13 <div class="u-cover u-cover-1"> 14 <img class="j-flag" src="http://p1.music.126.net/If644P7ZrfPm_qcvtYyfzg==/18936888765458653.jpg?param=140y140" /> 15 <a title="鞋子好看｜国产自赏摇滚噪音流行" href="/playlist?id=721462105" class="msk"></a> 16 <div class="bottom"> 17 <a class="icon-play f-fr" title="播放" href="javascript:;" data-res-type="13" data-res-id="721462105" data-res-action="play"></a> 18 <span class="icon-headset"></span> 19 <span class="nb">77652</span> 20 </div> 21 </div> <p class="dec"> <a title="鞋子好看｜国产自赏摇滚噪音流行" href="/playlist?id=721462105" class="tit f-thide s-fc0">鞋子好看｜国产自赏摇滚噪音流行</a> </p> <p><span class="s-fc4">by</span> <a title="原创君" href="/user/home?id=201586" class="nm nm-icn f-thide s-fc3">原创君</a> <sup class="u-icn u-icn-1 "></sup> </p> </li> 22 </ul>
开始解析html源码
首先实例化一个etree.HTMLParser对象，对html源码简单做下处理，创建cssselect.CSSSelector CSS选择器对象，搜索出无序列表ul下的所有li元素（_Element元素对象），再通过sel(document)遍历所有的_Element对象，使用find方法
find(self, path, namespaces=None) Finds the first matching subelement, by tag name or path. (lxml.ettr/lxml.cssselect 详细API请转义官网http://lxml.de/api/index.html)
通过xpath找到li的子元素img和a,通过_Element的属性attrib获取到属性字典，成功获取到歌单的图片链接，歌单列表链接和歌单名称。
1 from lxml import etree, cssselect 2 3 html = ‘‘‘上面提取的html源码‘‘‘ 4 parser = etree.HTMLParser(remove_blank_text=True) 5 document = etree.fromstring(html_doc, parser) 6 7 sel = cssselect.CSSSelector(‘#m-pl-container > li‘) 8 for e in sel(document): 9 img = e.find(‘.//div/img‘)10 img_url = img.attrib[‘src‘]11 a_msk = e.find(".//div/a[@class=‘msk‘]")12 musicList_url = ‘http:/%s‘ % a_msk.attrib[‘href‘]13 musicList_name = a_msk.attrib[‘title‘]14 print(img_url,musicList_url,musicList_name)
Python爬虫基础之lxml
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