662次阅读 | 发布于5年以前

以前讲过利用phantomjs做爬虫抓网页 http://www.jb51.net/article/55789.htm 是配合选择器做的

利用 beautifulSoup(文档：http://www.crummy.com/software/BeautifulSoup/bs4/doc/)这个python模块，可以很轻松的抓取网页内容


    # coding=utf-8
    import urllib
    from bs4 import BeautifulSoup

    url ='http://www.baidu.com/s'
    values ={'wd':'网球'}
    encoded_param = urllib.urlencode(values)
    full_url = url +'?'+ encoded_param
    response = urllib.urlopen(full_url)
    soup =BeautifulSoup(response)
    alinks = soup.find_all('a')

上面可以抓取百度搜出来结果是网球的记录。

beautifulSoup内置了很多非常有用的方法。

几个比较好用的特性：

构造一个node元素

复制代码 代码如下:

soup = BeautifulSoup('Extremely bold')
tag = soup.b
type(tag)

<class 'bs4.element.Tag'>

属性可以使用attr拿到，结果是字典

复制代码 代码如下:

tag.attrs

{u'class': u'boldest'}

或者直接tag.class取属性也可。

也可以自由操作属性


    tag['class'] = 'verybold'
    tag['id'] = 1
    tag
    # <blockquote class="verybold" id="1">Extremely bold</blockquote>

    del tag['class']
    del tag['id']
    tag
    # <blockquote>Extremely bold</blockquote>

    tag['class']
    # KeyError: 'class'
    print(tag.get('class'))
    # None

还可以随便操作，查找dom元素，比如下面的例子

1.构建一份文档


    html_doc = """
    <html><head><title>The Dormouse's story</title></head>

    <p><b>The Dormouse's story</b></p>

    <p>Once upon a time there were three little sisters; and their names were
    <a href="http://example.com/elsie" id="link1">Elsie</a>,
    <a href="http://example.com/lacie" id="link2">Lacie</a> and
    <a href="http://example.com/tillie" id="link3">Tillie</a>;
    and they lived at the bottom of a well.</p>

    <p>...</p>
    """

    from bs4 import BeautifulSoup
    soup = BeautifulSoup(html_doc)

2.各种搞


    soup.head
    # <head><title>The Dormouse's story</title></head>
    soup.title
    # <title>The Dormouse's story</title>
    soup.body.b
    # <b>The Dormouse's story</b>
    soup.a
    # <a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>
    soup.find_all('a')
    # [<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>,
    # <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>,
    # <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>]
    head_tag = soup.head
    head_tag
    # <head><title>The Dormouse's story</title></head>

    head_tag.contents
    [<title>The Dormouse's story</title>]

    title_tag = head_tag.contents[0]
    title_tag
    # <title>The Dormouse's story</title>
    title_tag.contents
    # [u'The Dormouse's story']
    len(soup.contents)
    # 1
    soup.contents[0].name
    # u'html'
    text = title_tag.contents[0]
    text.contents

    for child in title_tag.children:
      print(child)
    head_tag.contents
    # [<title>The Dormouse's story</title>]
    for child in head_tag.descendants:
      print(child)
    # <title>The Dormouse's story</title>
    # The Dormouse's story

    len(list(soup.children))
    # 1
    len(list(soup.descendants))
    # 25
    title_tag.string
    # u'The Dormouse's story'

python利用beautifulSoup实现爬虫

<class 'bs4.element.Tag'>

{u'class': u'boldest'}