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自从大一开始就想在博客专门建立一个分类,深度总结一下爬虫技术相关的东西,但是一直拖到现在。大二马上要结束了,准备从暑假开始认真总结,每一篇文章都争取带一个小案例。给学弟们作参考用~
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requests是一个作为Python构建的优雅而简单的HTTP库。目前它使用了Apache2 Licensed许可证,requests在Python一些基本库上进行了高度封装。中文文档:http://docs.python-requests.org/zh_CN/latest/
pip install requests
requests.get(url, params=None, **kwargs)
# 发送一个get请求到服务器端
# url接收一个URL地址
# parmas接收一个字典对象
# 返回一个请求对象
requests.options(url, **kwargs)
# 发送一个options请求到服务器端
# url接收一个URL地址
requests.head(url, **kwargs)
# 发送一个head请求到服务器端
# url接收一个URL地址
requests.post(url, data=None, json=None, **kwargs)
# 发送一个post请求到服务器端
# url接收一个URL地址
# data接收一个字典、字节或者是一个文件对象
# json接收一个json数据
requests.put(url, data=None, **kwargs)
# 发送一个put请求到服务器端
# url接收一个URL地址
# data接收一个字典、字节或者是一个文件对象
requests.patch(url, data=None, **kwargs)
# 发送一个patch请求到服务器端
# url接收一个URL地址
# data接收一个字典、字节或者是文件对象
requests.delete(url, **kwargs)
# 发送一个delete请求到服务器端
# url接收一个URL地址
requests.request(method, url, **kwargs)
# 发送一个请求
# method指定请求的方法
# url接收一个URL地址
# params接收一个字典、字节或者是文件对象
# data接收一个使用元组构成的列表[(key, value)]或者是字典、字节或者是文件对象
# json接收一个json数据
# headers接收一个字典,用于构成请求头
# cookies接收一个cookie对象
# files接收一个文件对象
# auth接收一个元组,用来身份认证
# timeout接收一个浮点数或者是元组
# allow_redirects接收一个布尔值,默认是True,是否开启重定向
# proxies 接收代理的url
# verify 是否启用安全认证
# stream 是否使用数据流的方式传输文件
# cert 使用证书文件,如果是pem文件,则(xxx.pem),如果是crt文件和key文件,则('xxx.crt', 'xxx.key')
# -*- coding: utf-8 -*-
"""
requests.api
This module implements the Requests API.
:copyright: (c) 2012 by Kenneth Reitz.
:license: Apache2, see LICENSE for more details.
"""
from . import sessions
def request(method, url, **kwargs):
"""Constructs and sends a :class:`Request `.
:param method: method for the new :class:`Request` object.
:param url: URL for the new :class:`Request` object.
:param params: (optional) Dictionary, list of tuples or bytes to send
in the body of the :class:`Request`.
:param data: (optional) Dictionary, list of tuples, 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) ` 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 ` object
:rtype: requests.Response
Usage::
>>> import requests
>>> req = requests.request('GET', 'https://httpbin.org/get')
"""
# 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)
def get(url, params=None, **kwargs):
r"""Sends a GET request.
:param url: URL for the new :class:`Request` object.
:param params: (optional) Dictionary, list of tuples or bytes to send
in the body of the :class:`Request`.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
kwargs.setdefault('allow_redirects', True)
return request('get', url, params=params, **kwargs)
def options(url, **kwargs):
r"""Sends an OPTIONS request.
:param url: URL for the new :class:`Request` object.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
kwargs.setdefault('allow_redirects', True)
return request('options', url, **kwargs)
def head(url, **kwargs):
r"""Sends a HEAD request.
:param url: URL for the new :class:`Request` object.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
kwargs.setdefault('allow_redirects', False)
return request('head', url, **kwargs)
def post(url, data=None, json=None, **kwargs):
r"""Sends a POST request.
:param url: URL for the new :class:`Request` object.
:param data: (optional) Dictionary, list of tuples, bytes, or file-like
object to send in the body of the :class:`Request`.
:param json: (optional) json data to send in the body of the :class:`Request`.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
return request('post', url, data=data, json=json, **kwargs)
def put(url, data=None, **kwargs):
r"""Sends a PUT request.
:param url: URL for the new :class:`Request` object.
:param data: (optional) Dictionary, list of tuples, bytes, or file-like
object to send in the body of the :class:`Request`.
:param json: (optional) json data to send in the body of the :class:`Request`.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
return request('put', url, data=data, **kwargs)
def patch(url, data=None, **kwargs):
r"""Sends a PATCH request.
:param url: URL for the new :class:`Request` object.
:param data: (optional) Dictionary, list of tuples, bytes, or file-like
object to send in the body of the :class:`Request`.
:param json: (optional) json data to send in the body of the :class:`Request`.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
return request('patch', url, data=data, **kwargs)
def delete(url, **kwargs):
r"""Sends a DELETE request.
:param url: URL for the new :class:`Request` object.
:param \*\*kwargs: Optional arguments that ``request`` takes.
:return: :class:`Response ` object
:rtype: requests.Response
"""
return request('delete', url, **kwargs)
Beautiful Soup是一个用于从HTML和XML文件中提取数据的Python库。它能够通过你喜欢的转换器实现惯用的文档导航,查找,修改文档的方式.Beautiful Soup会帮你节省数小时甚至数天的工作时间。中文文档:https://www.crummy.com/software/BeautifulSoup/bs4/doc.zh/
apt-get install Python-bs4
easy_install beautifulsoup4
pip install beautifulsoup4
下载地址:https://www.crummy.com/software/BeautifulSoup/bs4/download/4.0/
首先解压下载的源码压缩包,进入源码目录,执行:python setup.py install
apt-get install Python-lxml
easy_install lxml
pip install lxml
apt-get install Python-html5lib
easy_install html5lib
pip install html5lib
解析器 | 使用方法 | 优点 | 缺点 |
---|---|---|---|
Python标准库 | BeautifulSoup(markup, "html.parser") | Python的内置标准库,执行速度适中, 文档容错能力强 | Python 2.7.3 or 3.2.2)前的版本中文档容错能力差 |
lxml HTML 解析器 | BeautifulSoup(markup, "lxml") | 速度快,文档容错能力强 | 需要安装C语言库 |
lxml XML 解析器 | BeautifulSoup(markup, ["lxml", "xml"]) BeautifulSoup(markup, "xml") | 速度快,唯一支持XML的解析器 | 需要安装C语言库 |
html5lib | BeautifulSoup(markup, "html5lib") | 最好的容错性,以浏览器的方式解析文档,生成HTML5格式的文档 | 速度慢,不依赖外部扩展 |
从上表可知,推荐使用lxml解析器效率更高,但是xml或html文档的格式不正确的话返回的结果可能不正确。
from bs4 import BeautifulSoup
soup = BeautifulSoup(open("index.html")) # 直接打开本地html文件
soup = BeautifulSoup("data") #传入html文本
Beautiful Soup将HTML或XML文件转换为树形结构,每个节点都是Python对象。总共可以分为四种:
标签对象
tag = soup.b
tag.name
tag.attrs
来操作属性。可遍历的字符串NavigableString对象
unicode()
方法将其转换为Unicode字符串。unicode_string = unicode(tag.string)
replace_with()
方法被替换成为其他的字符串。BeautifulSoup对象
soup.name
属性的值是:u'[document]'
。注释及特殊字符串Comment对象
Comment 对象是一个特殊类型的 NavigableString 对象
markup = ""
soup = BeautifulSoup(markup)
comment = soup.b.string
type(comment)
#
print(soup.b.prettify()) # 输出成为了特殊的格式
#
#
#
属性及方法名称 | 释义 |
---|---|
soup.head | 获取<head></head> |
soup.title | 获取<title></title> |
soup.TagName | 获取< TagName> TagName> |
soup.find_all(‘TagName’) | 获取所有TagName的标签 |
tag.contents | 将tag子节点以列表的方式输出 |
tag.children | 返回一个tag子节点的可迭代生成器对象 |
tag.descendants | 属性可以对所有tag的子孙节点进行递归循环 |
tag.string | 获取tag中的字符串内容 |
tag.strings | 循环获取tag中的字符串内容 |
tag.stripped_strings | 功能类似于tag.strings ,但是具有除去多余空白字符串的功能 |
tag.parent | 获取父节点对象 |
tag.parents | 获取父节点对象可迭代生成器对象 |
tag.next_sibling | 获取下一个兄弟节点对象 |
tag.previous_sibling | 获取上一个兄弟节点对象 |
tag.next_siblings | 获取向下的所有兄弟节点的可迭代生成器对象 |
tag.previous_siblings | 获取向上的所有兄弟节点的可迭代生成器对象 |
tag.next_element | 指向解析过程中下一个被解析的对象 |
tag.previous_element | 指向解析过程中上一个被解析的对象 |
tag.next_elements | 指向解析过程中上面所有被解析对象的集合 |
tag.previous_elements | 指向解析过程中下面被解析对象的集合 |
tag.find_all(‘TagName’) | 查找所有与TagName匹配的节点 |
tag.find_all([‘TagName1’, ‘TagName2’]) | 查找所有与列表中TagName 相匹配的节点 |
tag.find_all(True) | 返回所有可以匹配的值 |
tag.find_all(FuncName) | 接收一个方法名称,如果这个方法返回True表示当前的元素匹配并且找到 |
def has_class_but_no_id(tag):
return tag.has_attr('class') and not tag.has_attr('id')
soup.find_all(has_class_but_no_id)
tag.find_all(Key=’Value) # 搜索所有Key的值是Value的标签
soup.find_all(Key=re.compile("RegExp"), Key='Value') # 结合正则表达式使用并且是或的逻辑关系
tag.find_all(text=’xxx’) # 使用text参数可以搜索文档中的字符串内容
tag.find_all(text=[‘xxx’, ‘xxx’, ]) # text参数可以接受字符串、正则、列表和布尔值
tag.find_all(‘TagName’, limit=Number) # 返回Number个符合的标签
tag.find_all(‘TagName’, recursive=True/False) # 是否只匹配直接子节点
tag.find( name , attrs , recursive , text , **kwargs ) # 直接返回一个结果,匹配不到时返回None,而find_all()返回空列表[]
# 类似的方法还有:
tag.find_parents()
tag.find_parent()
tag.find_next_siblings()
tag.find_next_sibling()
tag.find_previous_siblings()
tag.find_previous_sibling()
tag.find_all_next()
tag.find_next()
tag.find_all_previous()
tag.find_previous()
# Beautiful Soup支持大部分的CSS选择器,即tag.select():
tag.append(“Content”) # 向标签中添加内容
tag.new_string() # 创建新的字符串对象
tag.new_tag() # 创建新的标签对象
tag.insert() # 插入标签对象
tag.insert_before() # 在tag标签之前插入新的标签对象
tag.insert_after() # 在tag标签之后插入新的标签对象
tag. clear() # 清除当前tag的内容
tag. extract() # 将当前的tag从文档树中删除,并且返回该tag对象
tag. decompose() # 从当前的文档树中移除,并且完全销毁该tag对象
tag. replace_with() # 替换该tag对象
tag. wrap() # 用传入的tag对象包装指定的tag对象
tag. unwrap() # 取消使用上层tag对象的包装,并返回被移除的上层tag对象
tag. prettify() # 将文档树格式化后使用Unicode编码输出
tag. get_text() # 获取tag对象中的内容
# -*- coding:utf8 -*-
import requests
from bs4 import BeautifulSoup
# 用户名和密码
username = 'xxx'
password = 'xxx'
# 请求头
header = {
'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8',
'Accept-Encoding': 'gzip, deflate, br',
'Accept-Language': 'zh-CN,zh;q=0.9',
'Connection': 'keep-alive',
'Host': 'github.com',
'Referer': "https://github.com/xvGe/xvGe.github.io",
'Upgrade-Insecure-Requests': '1',
'User-Agent': "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36",
}
# 登录
response = requests.request('get', 'https://github.com/login', headers=header)
soup = BeautifulSoup(response.text, features='lxml')
# 获取登录token
token = soup.find(name='input', attrs={'name': "authenticity_token"})['value']
# 获取cookie
cookie = response.cookies.get_dict()
# 提交的登录数据
formData = {
'commit': 'Sign in',
'utf8': '✓',
'authenticity_token': token,
'login': username,
'password': password,
}
# 提交登录数据
response = requests.request('post', 'https://github.com/session', data=formData, cookies=cookie, headers=header)
response.close()