【零基础学爬虫】requests库详解

【1】Requests简介

• Requests 是⽤用Python语⾔言编写，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工作，完全满足
  HTTP 测试需求。
• ⼀句话：Requests是Python实现的简单易用的HTTP库
  #####Request的安装
  pip install requests
  #Requests实战
  ###1.发起HTTP 请求

import requests
response = requests.get('https://www.baidu.com/')
print(type(response))
print(response.status_code)
print(type(response.text))
print(response.text)
print(response.cookies)

2.各类请求方式

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')

2.基本的get请求

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

3.带参数GET请求

import requests
response = requests.get("http://httpbin.org/get?name=germey&age=22")
print(response.text)

上面这种拼接参数的方式可能不太方便，下面是另外一种带参数get请求发起的方式，与上面是等价的。

import requests
data = {
    'name': 'germey',
    'age': 22
}
response = requests.get("http://httpbin.org/get", params=data)
print(response.text)

4.解析json

import requests
import json
response = requests.get("http://httpbin.org/get")
print(type(response.text))#str格式
print(response.json())#json格式输出
print(json.loads(response.text))#和上结果一样
print(type(response.json()))#json是dict格式，即字典格式

5.获取二进制数据

import requests
response = requests.get("https://github.com/favicon.ico")
print(type(response.text), type(response.content))#str和bytes格式
print(response.text)#乱码
print(response.content)#二进制字节流

保存图片：

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

6.添加headers

在写爬虫的时候，如果不加headers，可能会服务器拒绝访问，如：

import requests
response = requests.get("https://www.zhihu.com/explore")
print(response.text)#response中的状态码是400，错误请求

添加headers

import requests
headers = {
    'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36'
}
response = requests.get("https://www.zhihu.com/explore", headers=headers)
print(response.text)#返回正常结果

7.基本的post请求

post请求需要用户携带一些数据，典型的就是用户登录

import requests
data = {'name': 'germey', 'age': '22'}
response = requests.post("http://httpbin.org/post", data=data)
print(response.text)

---

【2】response

1.response的主要属性

import requests
response = requests.get('http://www.jianshu.com')
print(type(response.status_code), response.status_code)
print(type(response.headers), response.headers)
print(type(response.cookies), response.cookies)
print(type(response.url), response.url)
print(type(response.history), response.history)

2.状态码判断

import requests

response = requests.get('http://www.jianshu.com/hello.html')
exit() if not response.status_code == requests.codes.not_found else print('404 Not Found')

import requests

response = requests.get('http://www.jianshu.com')
exit() if not response.status_code == 200 else print('Request Successfully')

3.常见的状态码：这也是面试常问的问题

100: (‘continue’,),
101: (‘switching_protocols’,),
102: (‘processing’,),
103: (‘checkpoint’,),
122: (‘uri_too_long’, ‘request_uri_too_long’),

200: (‘ok’, ‘okay’, ‘all_ok’, ‘all_okay’, ‘all_good’, ‘\o/’, ‘✓’),
201: (‘created’,),
202: (‘accepted’,),
203: (‘non_authoritative_info’, ‘non_authoritative_information’),
204: (‘no_content’,),
205: (‘reset_content’, ‘reset’),
206: (‘partial_content’, ‘partial’),
207: (‘multi_status’, ‘multiple_status’, ‘multi_stati’, ‘multiple_stati’),
208: (‘already_reported’,),
226: (‘im_used’,),

Redirection.

300: (‘multiple_choices’,),
301: (‘moved_permanently’, ‘moved’, ‘\o-’),
302: (‘found’,),
303: (‘see_other’, ‘other’),
304: (‘not_modified’,),
305: (‘use_proxy’,),
306: (‘switch_proxy’,),
307: (‘temporary_redirect’, ‘temporary_moved’, ‘temporary’),
308: (‘permanent_redirect’,
‘resume_incomplete’, ‘resume’,), # These 2 to be removed in 3.0

Client Error.

400: (‘bad_request’, ‘bad’),
401: (‘unauthorized’,),
402: (‘payment_required’, ‘payment’),
403: (‘forbidden’,),
404: (‘not_found’, ‘-o-’),
405: (‘method_not_allowed’, ‘not_allowed’),
406: (‘not_acceptable’,),
407: (‘proxy_authentication_required’, ‘proxy_auth’, ‘proxy_authentication’),
408: (‘request_timeout’, ‘timeout’),
409: (‘conflict’,),
410: (‘gone’,),
411: (‘length_required’,),
412: (‘precondition_failed’, ‘precondition’),
413: (‘request_entity_too_large’,),
414: (‘request_uri_too_large’,),
415: (‘unsupported_media_type’, ‘unsupported_media’, ‘media_type’),
416: (‘requested_range_not_satisfiable’, ‘requested_range’, ‘range_not_satisfiable’),
417: (‘expectation_failed’,),
418: (‘im_a_teapot’, ‘teapot’, ‘i_am_a_teapot’),
421: (‘misdirected_request’,),
422: (‘unprocessable_entity’, ‘unprocessable’),
423: (‘locked’,),
424: (‘failed_dependency’, ‘dependency’),
425: (‘unordered_collection’, ‘unordered’),
426: (‘upgrade_required’, ‘upgrade’),
428: (‘precondition_required’, ‘precondition’),
429: (‘too_many_requests’, ‘too_many’),
431: (‘header_fields_too_large’, ‘fields_too_large’),
444: (‘no_response’, ‘none’),
449: (‘retry_with’, ‘retry’),
450: (‘blocked_by_windows_parental_controls’, ‘parental_controls’),
451: (‘unavailable_for_legal_reasons’, ‘legal_reasons’),
499: (‘client_closed_request’,),

Server Error.

500: (‘internal_server_error’, ‘server_error’, ‘/o\’, ‘✗’),
501: (‘not_implemented’,),
502: (‘bad_gateway’,),
503: (‘service_unavailable’, ‘unavailable’),
504: (‘gateway_timeout’,),
505: (‘http_version_not_supported’, ‘http_version’),
506: (‘variant_also_negotiates’,),
507: (‘insufficient_storage’,),
509: (‘bandwidth_limit_exceeded’, ‘bandwidth’),
510: (‘not_extended’,),
511: (‘network_authentication_required’, ‘network_auth’, ‘network_authentication’),

---

【3】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

response = requests.get("https://www.baidu.com")
print(response.cookies)
for key, value in response.cookies.items():
    print(key + '=' + value)

(3)session可以维持会话信息

import requests

s = requests.Session()
s.get('http://httpbin.org/cookies/set/number/123456789')#供测试的网址 
#用session维持会话信息，相对于在一个浏览器中操作
response = s.get('http://httpbin.org/cookies')
print(response.text)

输出：

{
“cookies”: {
“number”: “123456789”
}
}

(4)证书验证

现在很多网站都需要证书的验证，没有证书会出现“你访问的不是一个私密链接”之类的错误。对于Https协议，直首先会检查证书是否合法，如果证书不合法，则会抛出：SSLError。针对这一点有两种措施：
下面这种方法：在访问的时候，设置不进行证书的验证，此时返回状态码200，但是依旧会有警告。

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

消除警告信息：

import requests
from requests.packages import urllib3
urllib3.disable_warnings()
response = requests.get('https://www.12306.cn', verify=False)
print(response.status_code)

【2】手动指定证书

import requests

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

(5)代理的设置

import requests

proxies = {
  "http": "http://127.0.0.1:9743",
  "https": "https://127.0.0.1:9743",
}
response = requests.get("https://www.taobao.com", proxies=proxies)
print(response.status_code)

对于需要用户名和密码的代理

import requests

proxies = {
    "http": "http://user:[email protected]:9743/",#指定好用户名和密码
}
response = requests.get("https://www.taobao.com", proxies=proxies)
print(response.status_code)

socks代理：先安装该模块

pip3 install 'requests[socks]'

代理设置

proxies = {
    'http': 'socks5://127.0.0.1:9742',
    'https': 'socks5://127.0.0.1:9742'
}
response = requests.get("https://www.taobao.com", proxies=proxies)
print(response.status_code)

(6) 超时设置

import requests
from requests.exceptions import ReadTimeout
try:
    response = requests.get("http://httpbin.org/get", timeout = 0.5)
    print(response.status_code)
except ReadTimeout:

###(7)需要登录认证才能访问的网站

import requests
from requests.auth import HTTPBasicAuth

r = requests.get('http://120.27.34.24:9001', auth=HTTPBasicAuth('user', '123'))
print(r.status_code)

下面与上面等价：

import requests

r = requests.get('http://120.27.34.24:9001', auth=('user', '123'))
print(r.status_code)

(8) 异常处理

import requests
from requests.exceptions import ReadTimeout, ConnectionError, RequestException
try:
    response = requests.get("http://httpbin.org/get", timeout = 0.5)
    print(response.status_code)
except ReadTimeout:
    print('Timeout')
except ConnectionError:
    print('Connection error')
except RequestException:
    print('Error')

上面就是request常用的一些方法介绍了

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