python 爬虫之BeautifulSoup

时间 2019-12-13

标签 python 爬虫 beautifulsoup 栏目 Python 繁體版

原文原文链接

BeautifulSoup是一个模块，该模块用于接收一个HTML或XML字符串，而后将其进行格式化，以后即可以使用他提供的方法进行快速查找指定元素，从而使得在HTML或XML中查找指定元素变得简单。html

 
        from  
        bs4  
        import  
        BeautifulSoup 
       
        html_doc  
        =  
        """ 
       
        <html><head><title>The Dormouse's story</title></head> 
       
        <body> 
       
        asdf 
       
        <div class="title"> 
       
        <b>The Dormouse's story总共</b> 
       
        <h1>f</h1> 
       
        </div> 
       
        <div class="story">Once upon a time there were three little sisters; and their names were 
       
        <a  class="sister0" id="link1">Els<span>f</span>ie</a>, 
       
        <a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and 
       
        <a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>; 
       
        and they lived at the bottom of a well.</div> 
       
        ad<br/>sf 
       
        <p class="story">...</p> 
       
        </body> 
       
        </html> 
       
        """ 
       
        soup  
        =  
        BeautifulSoup(html_doc, features 
        = 
        "lxml" 
        ) 
       
        # 找到第一个a标签 
       
        tag1  
        =  
        soup.find(name 
        = 
        'a' 
        ) 
       
        # 找到全部的a标签 
       
        tag2  
        =  
        soup.find_all(name 
        = 
        'a' 
        ) 
       
        # 找到id＝link2的标签 
       
        tag3  
        =  
        soup.select( 
        '#link2' 
        )

安装：python

 
         pip3 install beautifulsoup4

使用示例：git

 
         from  
         bs4  
         import  
         BeautifulSoup 
        
         html_doc  
         =  
         """ 
        
         <html><head><title>The Dormouse's story</title></head> 
        
         <body> 
        
         ... 
        
         </body> 
        
         </html> 
        
         """ 
        
         soup  
         =  
         BeautifulSoup(html_doc, features 
         = 
         "lxml" 
         )

一：对象种类github

　　（1）Tag　　 app

　　标记ide

　　soup对象自己比较特殊，它的name为[document]，对于其余内部标记，输出的值为标记自己的名称spa

抽取title:  print soup.title
抽取a    :  print soup.a
抽取p    :  print  soup.a

Tag不只能够获取name ，还能够修改name3d

soup.title.name = 'mytitle'

属性code

print soup.p['class']
print soup.p.get('class')

(2)NavigableStringorm

　获取标记内部的文字

print soup.p.string

转换成unicode字符串

　　unicode_string = unicode(soup.p.string)

(3 )BeautifulSoup

BeautifulSoup 对象表示的是一个文档的所有内容.大部分时候,能够把它看成 Tag 对象，是一个特殊的 Tag，咱们能够分别获取它的类型，名称，以及属性来感觉一下

print type(soup.name)

(4)Comment

　　Comment 对象是一个特殊类型的 NavigableString 对象，其实输出的内容仍然不包括注释符号

三：

　　遍历文档数：

　　(1)子节点

　　　　要点：.contents .children 属性

tag 的 .content 属性能够将tag的子节点以列表的方式输出

1 2	print soup.head.contents #[<title>The Dormouse's story</title>]

输出方式为列表，咱们能够用列表索引来获取它的某一个元素

1 2	print soup.head.contents[0] #<title>The Dormouse's story</title>

.children

它返回的不是一个 list，不过咱们能够经过遍历获取全部子节点。

咱们打印输出 .children 看一下，能够发现它是一个 list 生成器对象

1 2	print soup.head.children #<listiterator object at 0x7f71457f5710>

咱们怎样得到里面的内容呢？很简单，遍历一下就行了，代码及结果以下

1 2	for child in soup.body.children: print child

The Dormouse's story

Once upon a time there were three little sisters; and their names were

<a class="sister" href="http://example.com/elsie" id="link1"></a>,

<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> and

（2）父节点

它返回的不是一个 list，不过咱们能够经过遍历获取全部子节点。

咱们打印输出 .children 看一下，能够发现它是一个 list 生成器对象

1 2	print soup.head.children #<listiterator object at 0x7f71457f5710>

咱们怎样得到里面的内容呢？很简单，遍历一下就行了，代码及结果以下

1 2	for child in soup.body.children: print child

The Dormouse's story

Once upon a time there were three little sisters; and their names were

<a class="sister" href="http://example.com/elsie" id="link1"></a>,

<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> and

（2）全部子孙节点

1. name，标签名称

1 # tag = soup.find('a')
2 # name = tag.name # 获取
3 # print(name)
4 # tag.name = 'span' # 设置
5 # print(soup)

2. attr，标签属性

1 # tag = soup.find('a')
2 # attrs = tag.attrs    # 获取
3 # print(attrs)
4 # tag.attrs = {'ik':123} # 设置
5 # tag.attrs['id'] = 'iiiii' # 设置
6 # print(soup)

3. children,全部子标签

1 # body = soup.find('body')
2 # v = body.children

4. descendants,全部子子孙孙标签

1 # body = soup.find('body')
2 # v = body.descendants

5. clear,将标签的全部子标签所有清空（保留标签名）

1 # tag = soup.find('body')
2 # tag.clear()
3 # print(soup)

6. decompose,递归的删除全部的标签

1 # body = soup.find('body')
2 # body.decompose()
3 # print(soup)

7. extract,递归的删除全部的标签，并获取删除的标签

1 # body = soup.find('body')
2 # v = body.extract()
3 # print(soup)

8. decode,转换为字符串（含当前标签）；decode_contents（不含当前标签）

1 # body = soup.find('body')
2 # v = body.decode()
3 # v = body.decode_contents()
4 # print(v)

9. encode,转换为字节（含当前标签）；encode_contents（不含当前标签）

1 # body = soup.find('body')
2 # v = body.encode()
3 # v = body.encode_contents()
4 # print(v)

10. find,获取匹配的第一个标签

1 # tag = soup.find('a')
2 # print(tag)
3 # tag = soup.find(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie')
4 # tag = soup.find(name='a', class_='sister', recursive=True, text='Lacie')
5 # print(tag)

11. find_all,获取匹配的全部标签

 1 # tags = soup.find_all('a')
 2 # print(tags)
 3  
 4 # tags = soup.find_all('a',limit=1)
 5 # print(tags)
 6  
 7 # tags = soup.find_all(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie')
 8 # # tags = soup.find(name='a', class_='sister', recursive=True, text='Lacie')
 9 # print(tags)
10  
11  
12 # ####### 列表 #######
13 # v = soup.find_all(name=['a','div'])
14 # print(v)
15  
16 # v = soup.find_all(class_=['sister0', 'sister'])
17 # print(v)
18  
19 # v = soup.find_all(text=['Tillie'])
20 # print(v, type(v[0]))
21  
22  
23 # v = soup.find_all(id=['link1','link2'])
24 # print(v)
25  
26 # v = soup.find_all(href=['link1','link2'])
27 # print(v)
28  
29 # ####### 正则 #######
30 import re
31 # rep = re.compile('p')
32 # rep = re.compile('^p')
33 # v = soup.find_all(name=rep)
34 # print(v)
35  
36 # rep = re.compile('sister.*')
37 # v = soup.find_all(class_=rep)
38 # print(v)
39  
40 # rep = re.compile('http://www.oldboy.com/static/.*')
41 # v = soup.find_all(href=rep)
42 # print(v)
43  
44 # ####### 方法筛选 #######
45 # def func(tag):
46 # return tag.has_attr('class') and tag.has_attr('id')
47 # v = soup.find_all(name=func)
48 # print(v)
49  
50  
51 # ## get,获取标签属性
52 # tag = soup.find('a')
53 # v = tag.get('id')
54 # print(v)

12. has_attr,检查标签是否具备该属性

1 # tag = soup.find('a')
2 # v = tag.has_attr('id')
3 # print(v)

13. get_text,获取标签内部文本内容

1 # tag = soup.find('a')
2 # v = tag.get_text('id')
3 # print(v)

14. index,检查标签在某标签中的索引位置

1 # tag = soup.find('body')
2 # v = tag.index(tag.find('div'))
3 # print(v)
4  
5 # tag = soup.find('body')
6 # for i,v in enumerate(tag):
7 # print(i,v)

15. is_empty_element,是不是空标签(是否能够是空)或者自闭合标签，

判断是不是以下标签：'br' , 'hr', 'input', 'img', 'meta','spacer', 'link', 'frame', 'base'

1 # tag = soup.find('br')
2 # v = tag.is_empty_element
3 # print(v)

16. 当前的关联标签

 1 # soup.next
 2 # soup.next_element
 3 # soup.next_elements
 4 # soup.next_sibling
 5 # soup.next_siblings
 6  
 7 #
 8 # tag.previous
 9 # tag.previous_element
10 # tag.previous_elements
11 # tag.previous_sibling
12 # tag.previous_siblings
13  
14 #
15 # tag.parent
16 # tag.parents

17. 查找某标签的关联标签

 1 # tag.find_next(...)
 2 # tag.find_all_next(...)
 3 # tag.find_next_sibling(...)
 4 # tag.find_next_siblings(...)
 5  
 6 # tag.find_previous(...)
 7 # tag.find_all_previous(...)
 8 # tag.find_previous_sibling(...)
 9 # tag.find_previous_siblings(...)
10  
11 # tag.find_parent(...)
12 # tag.find_parents(...)
13  
14 # 参数同find_all

18. select,select_one, CSS选择器

 1 soup.select("title")
 2  
 3 soup.select("p nth-of-type(3)")
 4  
 5 soup.select("body a")
 6  
 7 soup.select("html head title")
 8  
 9 tag = soup.select("span,a")
10  
11 soup.select("head > title")
12  
13 soup.select("p > a")
14  
15 soup.select("p > a:nth-of-type(2)")
16  
17 soup.select("p > #link1")
18  
19 soup.select("body > a")
20  
21 soup.select("#link1 ~ .sister")
22  
23 soup.select("#link1 + .sister")
24  
25 soup.select(".sister")
26  
27 soup.select("[class~=sister]")
28  
29 soup.select("#link1")
30  
31 soup.select("a#link2")
32  
33 soup.select('a[href]')
34  
35 soup.select('a[href="http://example.com/elsie"]')
36  
37 soup.select('a[href^="http://example.com/"]')
38  
39 soup.select('a[href$="tillie"]')
40  
41 soup.select('a[href*=".com/el"]')
42  
43  
44 from bs4.element import Tag
45  
46 def default_candidate_generator(tag):
47     for child in tag.descendants:
48         if not isinstance(child, Tag):
49             continue
50         if not child.has_attr('href'):
51             continue
52         yield child
53  
54 tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator)
55 print(type(tags), tags)
56  
57 from bs4.element import Tag
58 def default_candidate_generator(tag):
59     for child in tag.descendants:
60         if not isinstance(child, Tag):
61             continue
62         if not child.has_attr('href'):
63             continue
64         yield child
65  
66 tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator, limit=1)
67 print(type(tags), tags)

19. 标签的内容

 1 # tag = soup.find('span')
 2 # print(tag.string)          # 获取
 3 # tag.string = 'new content' # 设置
 4 # print(soup)
 5  
 6 # tag = soup.find('body')
 7 # print(tag.string)
 8 # tag.string = 'xxx'
 9 # print(soup)
10  
11 # tag = soup.find('body')
12 # v = tag.stripped_strings  # 递归内部获取全部标签的文本
13 # print(v)

20.append在当前标签内部追加一个标签

 1 # tag = soup.find('body')
 2 # tag.append(soup.find('a'))
 3 # print(soup)
 4 #
 5 # from bs4.element import Tag
 6 # obj = Tag(name='i',attrs={'id': 'it'})
 7 # obj.string = '我是一个新来的'
 8 # tag = soup.find('body')
 9 # tag.append(obj)
10 # print(soup)

21.insert在当前标签内部指定位置插入一个标签

1 # from bs4.element import Tag
2 # obj = Tag(name='i', attrs={'id': 'it'})
3 # obj.string = '我是一个新来的'
4 # tag = soup.find('body')
5 # tag.insert(2, obj)
6 # print(soup)

22. insert_after,insert_before 在当前标签后面或前面插入

1 # from bs4.element import Tag
2 # obj = Tag(name='i', attrs={'id': 'it'})
3 # obj.string = '我是一个新来的'
4 # tag = soup.find('body')
5 # # tag.insert_before(obj)
6 # tag.insert_after(obj)
7 # print(soup)

23. replace_with 在当前标签替换为指定标签

1 # from bs4.element import Tag
2 # obj = Tag(name='i', attrs={'id': 'it'})
3 # obj.string = '我是一个新来的'
4 # tag = soup.find('div')
5 # tag.replace_with(obj)
6 # print(soup)

24. 建立标签之间的关系（但不会改变标签的位置）

1 # tag = soup.find('div')
2 # a = soup.find('a')
3 # tag.setup(previous_sibling=a)
4 # print(tag.previous_sibling)

25. wrap，将指定标签把当前标签包裹起来

 1 # from bs4.element import Tag
 2 # obj1 = Tag(name='div', attrs={'id': 'it'})
 3 # obj1.string = '我是一个新来的'
 4 #
 5 # tag = soup.find('a')
 6 # v = tag.wrap(obj1)
 7 # print(soup)
 8  
 9 # tag = soup.find('a')
10 # v = tag.wrap(soup.find('p'))
11 # print(soup)

26. unwrap，去掉当前标签，将保留其包裹的标签

1 # tag = soup.find('a')
2 # v = tag.unwrap()
3 # print(soup)

转载自：

http://www.cnblogs.com/wupeiqi/articles/6283017.html

python 爬虫 之BeautifulSoup

（2）父节点

（2）全部子孙节点

python 爬虫之BeautifulSoup