Beautiful Soup的简介(2)

1) find_all( name , attrs , recursive , text , **kwargs )
　find_all() 方法搜索当前tag的所有tag子节点,并判断是否符合过滤器的条件
　可根据标签名、属性、内容查找文档

html = """
<div class="panel">
    <div class="panel-heading">
        <h4>Hello</h4>
    <div class="panel-body">
        <ul class="list" id="list-1">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
        <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>
    </div>
</div>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'html5lib')
print(soup.find_all('ul'))      #find_all根据标签名'ul'都查找出来，放入列表当中
print(type(soup.find_all('ul')[0]))

[<ul class="list" id="list-1">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>, <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>]
<class 'bs4.element.Tag'>

html = """
<div class="panel">
    <div class="panel-heading">
        <h4>Hello</h4>
    <div class="panel-body">
        <ul class="list" id="list-1">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
        <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>
    </div>
</div>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'html5lib')
for ul in soup.find_all('ul'):  #通过两次for循环表示出来  
    print (ul.find_all('li'))

[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]

attrs

html = """
<div class="panel">
    <div class="panel-heading">
        <h4>Hello</h4>
    <div class="panel-body">
        <ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
        <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>
    </div>
</div>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'html5lib')
print(soup.find_all(attrs={'id':'list-1'}))
print(soup.find_all(attrs={'name':'elements'}))

[<ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>]
[<ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>]

html = """
<div class="panel">
    <div class="panel-heading">
        <h4>Hello</h4>
    <div class="panel-body">
        <ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
        <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>
    </div>
</div>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'html5lib')
print(soup.find_all(id='list-1'))
print(soup.find_all(class_='element')) #因为class在python中有特别意义，所有加多一个下滑线

[<ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>]
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>, <li class="element">Foo</li>, <li class="element">Bar</li>]

 
text

html = """
<div class="panel">
    <div class="panel-heading">
        <h4>Hello</h4>
    <div class="panel-body">
        <ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
        <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>
    </div>
</div>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'html5lib')
print(soup.find_all(text='Foo'))

['Foo', 'Foo']

2) find( name , attrs , recursive , text , **kwargs )

基本和find_all一样，只不过只查找一个标签，第一个标签

html = """
<div class="panel">
    <div class="panel-heading">
        <h4>Hello</h4>
    <div class="panel-body">
        <ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
        <ul class="list list-small" id="list-2">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
        </ul>
    </div>
</div>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'html5lib')
print(soup.find('ul'))
print(type(soup.find('ul')))
print(soup.find('page'))

<ul class="list" id="list-1" name="elements">
            <li class="element">Foo</li>
            <li class="element">Bar</li>
            <li class="element">Jay</li>
        </ul>
<class 'bs4.element.Tag'>
None

（3）find_parents()  find_parent()

find_all() 和 find() 只搜索当前节点的所有子节点,孙子节点等. find_parents() 和 find_parent() 用来搜索当前节点的父辈节点,搜索方法与普通tag的搜索方法相同,搜索文档搜索文档包含的内容

（4）find_next_siblings()  find_next_sibling()

这2个方法通过 .next_siblings 属性对当 tag 的所有后面解析的兄弟 tag 节点进行迭代, find_next_siblings()方法返回所有符合条件的后面的兄弟节点,find_next_sibling() 只返回符合条件的后面的第一个tag节点

（5）find_previous_siblings()  find_previous_sibling()

这2个方法通过 .previous_siblings 属性对当前 tag 的前面解析的兄弟 tag 节点进行迭代, find_previous_siblings() 方法返回所有符合条件的前面的兄弟节点, find_previous_sibling() 方法返回第一个符合条件的前面的兄弟节点

（6）find_all_next()  find_next()

这2个方法通过 .next_elements 属性对当前 tag 的之后的 tag 和字符串进行迭代, find_all_next() 方法返回所有符合条件的节点, find_next() 方法返回第一个符合条件的节点

（7）find_all_previous() 和 find_previous()

这2个方法通过 .previous_elements 属性对当前节点前面的 tag 和字符串进行迭代, find_all_previous() 方法返回所有符合条件的节点, find_previous()方法返回第一个符合条件的节点