python爬虫之requests+selenium+BeautifulSoup

前言：

• 环境配置：windows64、python3.4
• requests库基本操作：

1、安装：pip install requests

2、功能：使用 requests 发送网络请求，可以实现跟浏览器一样发送各种HTTP请求来获取网站的数据。

3、命令集操作：

import requests  # 导入requests模块

r = requests.get("https://api.github.com/events")  # 获取某个网页

# 设置超时，在timeout设定的秒数时间后停止等待响应
r2 = requests.get("https://api.github.com/events", timeout=0.001)

payload = {'key1': 'value1', 'key2': 'value2'}
r1 = requests.get("http://httpbin.org/get", params=payload)

print(r.url)  # 打印输出url

print(r.text)  # 读取服务器响应的内容

print(r.encoding)  # 获取当前编码

print(r.content)  # 以字节的方式请求响应体

print(r.status_code)  # 获取响应状态码
print(r.status_code == requests.codes.ok)  # 使用内置的状态码查询对象

print(r.headers)  # 以一个python字典形式展示的服务器响应头
print(r.headers['content-type'])  # 大小写不敏感，使用任意形式访问这些响应头字段

print(r.history)  # 是一个response对象的列表

print(type(r))  # 返回请求类型

• BeautifulSoup4库基本操作：

1、安装：pip install BeautifulSoup4

2、功能：Beautiful Soup 是一个可以从HTML或XML文件中提取数据的Python库。

3、命令集操作：

 import requests
 from bs4 import BeautifulSoup
 html_doc = """
 <html><head><title>The Dormouse's story</title></head>
 <body>
 <p class="title"><b>The Dormouse's story</b></p>

 <p class="story">Once upon a time there were three little sisters; and their names were
 <a href="http://example.com/elsie" class="sister" id="link1">Elsie</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.</p>

 <p class="story">...</p>
 """

 ss = BeautifulSoup(html_doc,"html.parser")
 print (ss.prettify())  #按照标准的缩进格式的结构输出
 print(ss.title)   # <title>The Dormouse's story</title>
 print(ss.title.name)   #title
 print(ss.title.string)   #The Dormouse's story
 print(ss.title.parent.name)   #head
 print(ss.p)   #<p class="title"><b>The Dormouse's story</b></p>
 print(ss.p['class'])   #['title']
 print(ss.a)   #<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>
 print(ss.find_all("a"))   #[。。。]
 print(ss.find(id = "link3"))   #<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>

 for link in ss.find_all("a"):
     print(link.get("link")) #获取文档中所有<a>标签的链接

 print(ss.get_text()) #从文档中获取所有文字内容

 import requests
 from bs4 import BeautifulSoup

 html_doc = """
 <html><head><title>The Dormouse's story</title></head>
 <body>
 <p class="title"><b>The Dormouse's story</b></p>
 <p class="story">Once upon a time there were three little sisters; and their names were
 <a href="http://example.com/elsie" class="sister" id="link1">Elsie</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.</p>

 <p class="story">...</p>
 """
 soup = BeautifulSoup(html_doc, 'html.parser')  # 声明BeautifulSoup对象
 find = soup.find('p')  # 使用find方法查到第一个p标签
 print("find's return type is ", type(find))  # 输出返回值类型
 print("find's content is", find)  # 输出find获取的值
 print("find's Tag Name is ", find.name)  # 输出标签的名字
 print("find's Attribute(class) is ", find['class'])  # 输出标签的class属性值

 print(find.string)  # 获取标签中的文本内容

 markup = "<b><!--Hey, buddy. Want to buy a used parser?--></b>"
 soup1 = BeautifulSoup(markup, "html.parser")
 comment = soup1.b.string
 print(type(comment))  # 获取注释中内容

• 小试牛刀：

 import requests
 import io
 import sys
 sys.stdout = io.TextIOWrapper(sys.stdout.buffer,encoding='gb18030') #改变标准输出的默认编码

 r = requests.get('https://unsplash.com') #像目标url地址发送get请求，返回一个response对象

 print(r.text) #r.text是http response的网页HTML

参考链接：

https://blog.csdn.net/u012662731/article/details/78537432

http://www.cnblogs.com/Albert-Lee/p/6276847.html

https://blog.csdn.net/enohtzvqijxo00atz3y8/article/details/78748531