初入requests

写在前面

Requests是用Python语言编写，基于urllib，采用Apache2 Licensed开源协议的HTTP库。它比urllib更加方便，可以节约我们大量的工作，完全满足HTTP测试需求。

一.请求——request详解

各种请求方法

import requests
requests.post('http://httpbin.org/post')
requests.put('http://httpbin.org/put')
requests.delete('http://httpbin.org/delete')
requests.head('http://httpbin.org/get')
requests.options('http://httpbin.org/get')

1.get请求

import requests
response = requests.get('http://httpbin.org/get')
print(response.text)

带参数的get请求

方法一

直接把参数写在URL里面，但是代码不美观。

import requests
response = requests.get("http://httpbin.org/get?name=lc-snail&age=18)
print(response.url)
#输出 ： http://httpbin.org/get?name=lc-snail&age=18

方法二

使用关键字 params,传入data字典来传递参数

import requests
data = {
        'name':'lc-snail',
        'age':18
        }
response = requests.get('http://httpbin.org/get',params=data)
print(response.url)
#输出 http://httpbin.org/get?name=lc-snail&age=18  ，由此可见，通过关键字params也可以实现传递参数

print(type(response))
# 返回的类型为<class 'requests.models.Response'>

print(response.cookies)
#返回的cookie类型为questsCookieJar[]>

2.post请求

import requests
data = {
        'name':'lc-snail',
        'age':18
        }
response = requests.post('http://httpbin.org/post',data=data)
print(response.text)
"""
输出 
{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "age": "18",
    "name": "lc-snail"
  },
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Content-Length": "20",
    "Content-Type": "application/x-www-form-urlencoded",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.23.0",
    "X-Amzn-Trace-Id": "Root=1-5ef7f84f-b27abe7201fc3bef06f6c423"
  },
  "json": null,
  "origin": "221.213.55.62",
  "url": "http://httpbin.org/post"
}
"""

3.解析Json

import requests
response = requests.get('http://httpbin.org/get')
print(response.text)
print('======================================')
print(response.json())
print('======================================')
print(type(response.json()))


"""
输出
{
  "args": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.23.0",
    "X-Amzn-Trace-Id": "Root=1-5ef7fdaf-e72b899874ee2408af8a4f42"
  },
  "origin": "221.213.55.62",
  "url": "http://httpbin.org/get"
}
======================================
{'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.23.0', 'X-Amzn-Trace-Id': 'Root=1-5ef7fdaf-e72b899874ee2408af8a4f42'}, 'origin': '221.213.55.62', 'url': 'http://httpbin.org/get'}      
======================================
<class 'dict'>
"""

这在ajax请求时比较常用

4.获取二进制数据

import requests
response = requests.get('https://www.cnblogs.com/favicon.ico')
print(type(response.text),type(response.content))
print(response.text)  #response.text是string类型，会出现乱码
print(response.content) #response.content是二进制流，

要把图片、视频、音频保存在本地需要保存二进制流

import requests
response = requests.get('https://www.cnblogs.com/favicon.ico')
with open('favicon.ico','wb') as f:
    f.write(response.content)
    f.close()

5.添加headers

不加headers，被识别出为爬虫，直接返回400 ，

import requests
response = requests.get('https://www.zhihu.com/explore')
print(response.status_code)

添加headers就可以访问成功

import requests
headers = {
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36'
        }
response = requests.get('https://www.zhihu.com/explore',headers=headers)
print(response.status_code)#输出200

二.响应——response详解

import requests
response = requests.get('http://www.baidu.com')
# 获取状态码
print(response.status_code)  
#获取headers
print(response.headers)
#获取cookies
print(response.cookies)
#或者url
print(response.url)
#获取history （请求历史）
print(response.history)

根据状态码判断是否请求成功

import requests
response = requests.get('http://www.baidu.com')
if response.status_code == 200:
     print('连接成功')
else:
     print('连接失败')

三.request高级操作

1.文件上传

import requests
files = {'file':open('favicon.ico','rb')}
response = requests.post('http://httpbin.org/post',files=files)
print(response.text)

2.获取cookie

import requests
headers = {
     'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36'
}
response = requests.get('https://www.baidu.com',headers=headers)
print(response.cookies)  #cookie是一个列表
print('========================')
#遍历所有cookie的name和value
for key,value in response.cookies.items():
    print(key + "=" + value)
#指定获取某个具体的cookie值
print('========================')
print(response.cookies['BAIDUID'])

"""
 <RequestsCookieJar[<Cookie BAIDUID=03C597A3B8610B57E33D0EF8C9EE0227:FG=1 for .baidu.com/>, <Cookie BIDUPSID=03C597A3B8610B57033E407A0397EFCB for .baidu.com/>, <Cookie H_PS_PSSID=32099_1432_31326_21093_32140_32046_32092_32109 for .baidu.com/>, <Cookie PSTM=1593312991 for .baidu.com/>, <Cookie BDSVRTM=0 for www.baidu.com/>, <Cookie BD_HOME=1 for www.baidu.com/>]>
========================
BAIDUID=03C597A3B8610B57E33D0EF8C9EE0227:FG=1
BIDUPSID=03C597A3B8610B57033E407A0397EFCB
H_PS_PSSID=32099_1432_31326_21093_32140_32046_32092_32109
PSTM=1593312991
BDSVRTM=0
BD_HOME=1
========================
03C597A3B8610B57E33D0EF8C9EE0227:FG=1 
"""

3.会话维持

模拟登录

import requests
cookies = {"name":"lc-snail"}
#这里使用关键字cookies把自己的cookie传给服务器，希望下一次使用requests.get时，返回这个cookie
r1 = requests.get('http://httpbin.org/cookies',cookies=cookies)
print(r1.text)
print('=========================')
r2 = response = requests.get('http://httpbin.org/cookies')
print(r2.text)  #输出的cookie为空
""" 
输出
{
  "cookies": {
    "name": "lc-snail"
  }
}

=========================
{
  "cookies": {}
}
"""

'''
实际上调用2次requests.get是互相独立的，相当于用不同的浏览器打开网页。如果想返回刚刚设置的cookie需要保持会话。
'''

解决方案

创建一个Session()对象,利用这个对象来实现模拟登录

import requests
s = requests.Session()
s.get('http://httpbin.org/cookies/set//1234567')
response = s.get('http://httpbin.org/cookies')
print(response.text)
'''
输出
返回值：{
 "cookies": {
 "number": "1234567"
 }
 }*
'''

4.证书验证

有时候打开https的网站，而这个网站提供的证书没有通过验证，那么抛出ssl错误导致程序中断。

如图所示

解决方法1——verify参数

为了防止这种情况，可以用varify参数，改为False（默认为True）不进行验证。可以通过验证，但是会报警告信息。

import requests
response = requests.get('https://www.12306.cn',verify=False)  
print(response.status_code)

消除警告信息

调用原生的urllib3中的disable_warnings()可以消除警告信息。

import requests
from requests.packages import urllib3
urllib3.disable_warnings()#调用原生的urllib3中的disable_warnings()可以消除警告信息。
response = requests.get('https://www.12306.cn',verify=False)
print(response.status_code)

解决方法2——手动导入证书和key

import requests

response = requests.get('https://www.12306.cn',cert={'parth/server.crt','/path/key'})
print(response.status_code)

注:

我们需要有 crt 和 key 文件，并且指定它们的路径。注意，本地私有证书的 key 必须是解密状态，加密状态的 key 是不支持的。

5.代理设置

import request
proxies = {
    "http":"http://127.0.0.1:9998",
    "https":"https://127.0.0.1:9998",
}
response = requests.get("https://www.taobao.com",proxies=proxies)
print(response.status_code)

有用户名密码的代理

import request
proxies = {
    "http":"http://user:password@127.0.0.1:9998",
    }
response = requests.get("https://www.taobao.com",proxies=proxies)
print(response.status_code)

除了HTTP代理之外也支持sock代理

import requests
proxies = {
    "http":"sock5://127.0.0.1:9998",
    "https":"sock5://127.0.0.1:9998",
}
response = requests.get("https://www.taobao.com",proxies=proxies)
print(response.status_code)

注：

如果要用sock代理需要安装sock库（pip3 install ’ requests[socks ］’）

6.超时设置

import requests
try:
    response = requests.get("http://httpbin.org/get",timeout=1)
    print(response.status_code)
except requests.ReadTimeout:
    print('Timeout')

认证设置

有些网站需要输入用户名和密码才能看到网站内容，则需要验证。

demo —— 传入一个HTTPBasicAuth 类

import requests

response = requests.get("http://httpbin.org/get",auth=HTTPBasicAuth('user','123'))
print(response.status_code)

demo —— 传入字典的方式

import requests
response = requests.get("http://httpbin.org/get",auth={'user':'123'})
print(response.status_code)

异常处理

import requests
from requests.exceptions import ReadTimeout,ConnectionError,RequestException
try:
    response = requests.get("http://httpbin.org/get",timeout=0.2)
    print(response.status_code)
except ReadTimeout:
    print('Timeout')
except ConnectionError:
    print("Con error")
except RequestException:
    print('Error')

参考

参考《Python 3网络爬虫开发实战》[崔庆才著]