4.爬虫 requests库讲解 GET请求 POST请求 响应

requests库相比于urllib库更好用！！！

0.各种请求方式

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')

*http://httpbin.org是一个http请求验证网站！

1.GET请求

• 带参数的get请求（两种方式是等效的）

import requests

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

########################

import requests

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

输出结果如下：

{
  "args": {
    "age": "22",
    "name": "germey"
  },
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.18.4"
  },
  "origin": "182.148.156.45, 182.148.156.45",
  "url": "https://httpbin.org/get?name=germey&age=22"
}

* params=data 对于get请求 添加附加的格外的信息，这个信息一般用字典来存储，可见返回的结果中args字段.

• 解析json

import requests
import json

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

输出结果如下：

<class 'str'>
{'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.18.4'}, 'origin': '182.148.156.45, 182.148.156.45', 'url': 'https://httpbin.org/get'}
{'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.18.4'}, 'origin': '182.148.156.45, 182.148.156.45', 'url': 'https://httpbin.org/get'}
<class 'dict'>

*网页返回的类型是str类型，但是有的很特殊，返回的是JSON格式的字符串.json()将JSON格式的字符串转换为字典。

*可以看到response.json()和json.loads(response.text)打印出来的结果是一样的！

*倘若网页返回的结果不是JSON格式的，便会出现解析错误，抛出json.decoder.JSONDecodeError的异常。

• 获取二进制数据

import requests

response = requests.get("https://github.com/favicon.ico")
print(type(response.text), type(response.content))
print(response.text)
print(response.content)

"""
#抓取并保存二进制数据(图片、视频、音频等文件)
with open('文件名称','wb') as f:
　　f.write(r.content)
"""

*图标地址一般都放在网络根目录下，名称为favicon.ico

*获取文本数据：response.text

*获取图片等二进制数据：response.content

• 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)

2.POST请求

• 带参数POST请求

import requests

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

• 添加headers

import requests

data = {'name': 'germey', 'age': ''}
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.post("http://httpbin.org/post", params=data, headers=headers)
print(response.text)
print(response.json())

输出结果如下：

{
  "args": {
    "age": "22",
    "name": "germey"
  },
  "data": "",
  "files": {},
  "form": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Content-Length": "0",
    "Host": "httpbin.org",
    "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"
  },
  "json": null,
  "origin": "101.206.170.234, 101.206.170.234",
  "url": "https://httpbin.org/post?name=germey&age=22"
}

{'args': {'age': '22', 'name': 'germey'}, 'data': '', 'files': {}, 'form': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Content-Length': '0', 'Host': 'httpbin.org', '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'}, 'json': None, 'origin': '101.206.170.234, 101.206.170.234', 'url': 'https://httpbin.org/post?name=germey&age=22'}

*可以看到GET和POST方式的带参数的请求和添加headers的方式差不多！

3.响应

• reponse属性

import requests

response = requests.get('http://www.jianshu.com')
print(type(response.status_code), response.status_code) #状态码
print(type(response.headers), response.headers) #响应头
print(type(response.cookies), response.cookies) #cookies值
print(type(response.url), response.url) #url
print(type(response.history), response.history) #请求历史

输出结果如下：

<class 'int'> 403
<class 'requests.structures.CaseInsensitiveDict'> {'Server': 'Tengine', 'Content-Type': 'text/html', 'Transfer-Encoding': 'chunked', 'Connection': 'keep-alive', 'Date': 'Tue, 09 Apr 2019 13:14:23 GMT', 'Vary': 'Accept-Encoding', 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains; preload', 'Content-Encoding': 'gzip', 'x-alicdn-da-ups-status': 'endOs,0,403', 'Via': 'cache29.l2cm12-6[17,0], cache8.cn389[77,0]', 'Timing-Allow-Origin': '*', 'EagleId': '7d412b4815548156634056180e'}
<class 'requests.cookies.RequestsCookieJar'> <RequestsCookieJar[]>
<class 'str'> https://www.jianshu.com/
<class 'list'> [<Response [301]>]

• 状态码判断

下面列出反悔码和相应的查询条件：

# 信息性状态码
100: ('continue',),
101: ('switching_protocols',),
102: ('processing',),
103: ('checkpoint',),
122: ('uri_too_long', 'request_uri_too_long'),

# 成功状态码
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.重定向
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.客户端错误
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.服务端错误
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'),

状态码用于判断请求是否成功，requests还提供了一个内置的状态码查询对象requests.codes。（两种写法都可以）

import requests

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

###################################
import requests

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