requests与BeautifulSoup

requests模块：

1、安装：pip install requests

2、使用request发送get请求：

import requests
paras = {
    'k1':'c1',
    'k2':'c2'
}
ret = requests.get('https://www.cnblogs.com/qiangayz/p/9563377.html')
print(ret.url)

ret = requests.get('https://www.cnblogs.com/qiangayz/p/9563377.html', params=paras)
print(ret.url)

3、使用request发送post请求：

import requests
import json

paras = {
    'k1':'v1',
    'k2':'v2',
}
requests.post('https://www.cnblogs.com/qiangayz/p/9563377.html')

headers_data = {
    'user-agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36'
}
requests.post('https://www.cnblogs.com/qiangayz/p/9563377.html',
              headers=headers_data,
              data=json.dumps(paras),
              )

4、requests初始化其他可选参数：

"""Constructs and sends a :class:`Request <Request>`.

    :param method: method for the new :class:`Request` object.
    :param url: URL for the new :class:`Request` object.
    :param params: (optional) Dictionary or bytes to be sent in the query string for the :class:`Request`.
    :param data: (optional) Dictionary or list of tuples ``[(key, value)]`` (will be form-encoded), bytes, or file-like object to send in the body of the :class:`Request`.
    :param json: (optional) A JSON serializable Python object to send in the body of the :class:`Request`.
    :param headers: (optional) Dictionary of HTTP Headers to send with the :class:`Request`.
    :param cookies: (optional) Dict or CookieJar object to send with the :class:`Request`.
    :param files: (optional) Dictionary of ``'name': file-like-objects`` (or ``{'name': file-tuple}``) for multipart encoding upload.
        ``file-tuple`` can be a 2-tuple ``('filename', fileobj)``, 3-tuple ``('filename', fileobj, 'content_type')``
        or a 4-tuple ``('filename', fileobj, 'content_type', custom_headers)``, where ``'content-type'`` is a string
        defining the content type of the given file and ``custom_headers`` a dict-like object containing additional headers
        to add for the file.
    :param auth: (optional) Auth tuple to enable Basic/Digest/Custom HTTP Auth.
    :param timeout: (optional) How many seconds to wait for the server to send data
        before giving up, as a float, or a :ref:`(connect timeout, read
        timeout) <timeouts>` tuple.
    :type timeout: float or tuple
    :param allow_redirects: (optional) Boolean. Enable/disable GET/OPTIONS/POST/PUT/PATCH/DELETE/HEAD redirection. Defaults to ``True``.
    :type allow_redirects: bool
    :param proxies: (optional) Dictionary mapping protocol to the URL of the proxy.
    :param verify: (optional) Either a boolean, in which case it controls whether we verify
            the server's TLS certificate, or a string, in which case it must be a path
            to a CA bundle to use. Defaults to ``True``.
    :param stream: (optional) if ``False``, the response content will be immediately downloaded.
    :param cert: (optional) if String, path to ssl client cert file (.pem). If Tuple, ('cert', 'key') pair.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response

    Usage::

      >>> import requests
      >>> req = requests.request('GET', 'http://httpbin.org/get')
      <Response [200]>
    """

    # By using the 'with' statement we are sure the session is closed, thus we
    # avoid leaving sockets open which can trigger a ResourceWarning in some
    # cases, and look like a memory leak in others.
    with sessions.Session() as session:
        return session.request(method=method, url=url, **kwargs)

　　

参数说明：

-- method：请求方式：post、get等

-- url ：请求的网址url

-- params：在url上传递的参数

　　例：

paras = {
    'k1':'c1',
    'k2':'c2'
}
requests.get('https://www.cnblogs.com/qiangayz/p/9563377.html', params=paras)
实际url是：
https://www.cnblogs.com/qiangayz/p/9563377.html?k1=c1&k2=c2

-- data：在请求体里面传递的数据，请求头为：

　　headers={'Content-Type': 'application/x-www-form-urlencoded'}

-- json：也是在请求题里面传递数据，与data不同的是请求头不一样，且json数据可以嵌套字典

　　请求头为：

　　headers={'Content-Type': 'application/x-www-form-urlencoded'}

-- headers:请求头

-- cookies：网站cookies

-- files：上传文件：

requests.post(
    url='127.0.0.1',
    files={
        'f1': open('xxx.txt', 'rb'), #文件名使用默认的
        'f2':('XXX.txt', open('xxx.txt', 'rb')) #使用定制的文件名
    }
)

　　

-- auth:简易认证，将与户名和密码加密之后放到请求头里面发送过去

-- timeout ：超时

-- allow_redirects：是否允许重定向

-- proxies：使用代理

-- stream：使用流

-- verify ：证书，http与https的区别，https可以使用证书来加密消息，该值可以是False或者True，False代表不接受证书，忽略证书

-- cert：证书文件

5、requests.session的使用：

保存客户端历史访问信息

import requests

session = requests.Session()

#首先登陆页面获取cookies
l1 = session.get(url='xxxxx')
#用户登录，携带上一次的cookies
l2 = session.post(
    url='xxx',
    data='',
)

　　

BeautifulSoup模块：

1、安装：

pip install beautifulsoup4

2、基本使用

from bs4 import BeautifulSoup
import htmldoc

html_doc = htmldoc.html_doc
soup = BeautifulSoup(html_doc,features='html.parser')
#找到一个a标签
tag1 = soup.find(name='a')
print(tag1.name,tag1.attrs)
#找到所有a标签
tag2 = soup.find_all(name='a')
print(tag2)
#找到id为inputuser的标签
tag3 = soup.select('#inputuser')[0]
print(tag3.name,tag3.attrs)

3、标签的方法：

1、tag1.name获取标签名称

　　tag1.name='span' 给标签赋值

2、tag1.attrs获取标签的属性值，字典类型

tag1.attrs=dict1设置值

　　tag1.attrs['id'] = 'a123'设置值

　　del tag1.attrs['id'] 删除属性

3、tags.children找子标签

from bs4 import BeautifulSoup
import htmldoc
from bs4.element import Tag

html_doc = htmldoc.html_doc
soup = BeautifulSoup(html_doc,features='html.parser')

tags = soup.find(name='body').children
tags_list = []
for item in tags:
    if type(item) == Tag:
        tags_list.append(item)

4、tag.descendants

tags = soup.find(name='body').descendants  #找子子孙孙，第一个递归完才开始找第二个
print(len(list(tags)))

　　

5、tag. clear,将标签的所有子标签清空（保留标签名）

6、tag.decompose,递归的删除所有的标签，（不保留当前标签名）

7、tag.extract,递归的删除所有的标签，并返回删除的标签，类似于列表的pop方法

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

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

10. find,获取匹配的第一个标签

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

11. find_all,获取匹配的所有标签

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# tags = soup.find_all('a') # print(tags)   # tags = soup.find_all('a',limit=1) # print(tags)   # tags = soup.find_all(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie') # # tags = soup.find(name='a', class_='sister', recursive=True, text='Lacie') # print(tags)     # ####### 列表 ####### # v = soup.find_all(name=['a','div']) # print(v)   # v = soup.find_all(class_=['sister0', 'sister']) # print(v)   # v = soup.find_all(text=['Tillie']) # print(v, type(v[0]))     # v = soup.find_all(id=['link1','link2']) # print(v)   # v = soup.find_all(href=['link1','link2']) # print(v)   # ####### 正则 ####### import re # rep = re.compile('p') # rep = re.compile('^p') # v = soup.find_all(name=rep) # print(v)   # rep = re.compile('sister.*') # v = soup.find_all(class_=rep) # print(v)   # rep = re.compile('http://www.oldboy.com/static/.*') # v = soup.find_all(href=rep) # print(v)   # ####### 方法筛选 ####### # def func(tag): # return tag.has_attr('class') and tag.has_attr('id') # v = soup.find_all(name=func) # print(v)     # ## get,获取标签属性 # tag = soup.find('a') # v = tag.get('id') # print(v)

12. has_attr,检查标签是否具有该属性

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

13. get_text,获取标签内部文本内容

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# tag = soup.find('a') # v = tag.get_text() # print(v)

14. index,检查标签在某标签中的索引位置

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# tag = soup.find('body') # v = tag.index(tag.find('div')) # print(v)   # tag = soup.find('body') # for i,v in enumerate(tag): # print(i,v)

15. is_empty_element,是否是空标签(是否可以是空)或者自闭合标签，

判断是否是如下标签：'br' , 'hr', 'input', 'img', 'meta','spacer', 'link', 'frame', 'base'

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

16. 当前的关联标签

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# soup.next # soup.next_element # soup.next_elements # soup.next_sibling # soup.next_siblings   # # tag.previous # tag.previous_element # tag.previous_elements # tag.previous_sibling # tag.previous_siblings   # # tag.parent # tag.parents

17. 查找某标签的关联标签

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# tag.find_next(...) # tag.find_all_next(...) # tag.find_next_sibling(...) # tag.find_next_siblings(...)   # tag.find_previous(...) # tag.find_all_previous(...) # tag.find_previous_sibling(...) # tag.find_previous_siblings(...)   # tag.find_parent(...) # tag.find_parents(...)   # 参数同find_all

18. select,select_one, CSS选择器

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soup.select("title")   soup.select("p nth-of-type(3)")   soup.select("body a")   soup.select("html head title")   tag = soup.select("span,a")   soup.select("head > title")   soup.select("p > a")   soup.select("p > a:nth-of-type(2)")   soup.select("p > #link1")   soup.select("body > a")   soup.select("#link1 ~ .sister")   soup.select("#link1 + .sister")   soup.select(".sister")   soup.select("[class~=sister]")   soup.select("#link1")   soup.select("a#link2")   soup.select('a[href]')   soup.select('a[href="http://example.com/elsie"]')   soup.select('a[href^="http://example.com/"]')   soup.select('a[href$="tillie"]')   soup.select('a[href*=".com/el"]')     from bs4.element import Tag   def default_candidate_generator(tag):     for child in tag.descendants:         if not isinstance(child, Tag):             continue         if not child.has_attr('href'):             continue         yield child   tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator) print(type(tags), tags)   from bs4.element import Tag def default_candidate_generator(tag):     for child in tag.descendants:         if not isinstance(child, Tag):             continue         if not child.has_attr('href'):             continue         yield child   tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator, limit=1) print(type(tags), tags)

19. 标签的内容

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# tag = soup.find('span') # print(tag.string)          # 获取 # tag.string = 'new content' # 设置 # print(soup)   # tag = soup.find('body') # print(tag.string) # tag.string = 'xxx' # print(soup)   # tag = soup.find('body') # v = tag.stripped_strings  # 递归内部获取所有标签的文本 # print(v)

20.append在当前标签内部追加一个标签

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# tag = soup.find('body') # tag.append(soup.find('a')) # print(soup) # # from bs4.element import Tag # obj = Tag(name='i',attrs={'id': 'it'}) # obj.string = '我是一个新来的' # tag = soup.find('body') # tag.append(obj) # print(soup)

21.insert在当前标签内部指定位置插入一个标签

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

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

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

23. replace_with 在当前标签替换为指定标签

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

24. 创建标签之间的关系

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# tag = soup.find('div') # a = soup.find('a') # tag.setup(previous_sibling=a) # print(tag.previous_sibling)

25. wrap，将指定标签把当前标签包裹起来

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# from bs4.element import Tag # obj1 = Tag(name='div', attrs={'id': 'it'}) # obj1.string = '我是一个新来的' # # tag = soup.find('a') # v = tag.wrap(obj1) # print(soup)   # tag = soup.find('a') # v = tag.wrap(soup.find('p')) # print(soup)

26. unwrap，去掉当前标签，将保留其包裹的标签

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

更多参数官方：http://beautifulsoup.readthedocs.io/zh_CN/v4.4.0/