爬虫3：requests库
一个简单易用的http库，多用于第一步，爬取网站源码
简单例子
import requests
response = requests.get('https://www.baidu.com/')
print(type(response))
print(response.status_code)
print(type(response.text)) //字符串类型
print(response.text)
print(response.cookies)
一. requests的几种请求方式
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')
1. 基本GET请求
2. 带参数的GET请求
import requests
response = requests.get("http://httpbin.org/get?name=germey&age=22")
print(response.text)
使用params参数简化操作
import requests
data = {
'name': 'germey',
'age': 22
}
response = requests.get("http://httpbin.org/get", params=data)
print(response.text)
3. 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())
4. 获取2进制数据
import requests
response = requests.get("https://github.com/favicon.ico")
print(type(response.text), type(response.content))
print(response.text) //和下面的做比较
print(response.content) //获取2进制内容
保存2进制文件
import requests
response = requests.get("https://github.com/favicon.ico")
with open('favicon.ico', 'wb') as f:
f.write(response.content)
f.close()
5. 添加headers
上面代码不加header内容会报错500，修改如下即可
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)
二. 基本POST请求
import requests
data = {'name': 'germey', 'age': '22'}
response = requests.post("http://httpbin.org/post", data=data)
print(response.text)
加一个header
import requests
data = {'name': 'germey', 'age': '22'}
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", data=data, headers=headers)
print(response.json())
三. 响应
1. response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
1）使用状态码相对应文本
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')
2）使用状态码数字
import requests
response = requests.get('http://www.jianshu.com')
exit() if not response.status_code == 200 else print('Request Successfully')
3）状态码对应文本
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'),
四. 高级操作
1. 文件上传，使用files参数
import requests
files = {'file': open('favicon.ico', 'rb')} //指定文件名为file
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) //列表形式
for key, value in response.cookies.items():
print(key + '=' + value)
3. 会话维持
模拟登陆
例子1，在测试网站httpbin.org中实验
import requests
requests.get('http://httpbin.org/cookies/set/number/123456789')
response = requests.get('http://httpbin.org/cookies')
print(response.text)
上面代码返回空，没获得cookie信息，原因是使用了2次requests.get方法，相当于开启了2个浏览器
例子2，在同一个浏览器中获得cookie，使用requests.Session()
import requests
s = requests.Session()
s.get('http://httpbin.org/cookies/set/number/123456789') //设置cookie
response = s.get('http://httpbin.org/cookies') //获得cookie
print(response.text)
返回结果如下
{"cookies":{"number":"123456789"}}
4. 证书验证,解决https问题
使用requests.get()方法来访问URL时，如果发现https证书不合法会报SSLError错误，并中断
解决方法为加一个verify=False参数，并禁止警报
import requests
from requests.packages import urllib3
urllib3.disable_warnings()
response = requests.get('https://www.12306.cn', verify=False)
print(response.status_code)
自己上传证书
import requests
response = requests.get('https://www.12306.cn', cert=('/path/server.crt', '/path/key'))
print(response.status_code)
5. 代理设置
1）无用户名和密码的代理
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)
2）有用户名和密码的代理
import requests
proxies = {
"http": "http://user:password@127.0.0.1:9743/",
}
response = requests.get("https://www.taobao.com", proxies=proxies)
print(response.status_code)
3）不是http,https代理，而是socks代理的情况
pip3 install 'requests[socks]'
import requests
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:
print('Timeout')
7. 认证设置
有些网站需要输入用户名和密码才能看到网页内容
方法1
import requests
from requests.auth import HTTPBasicAuth
r = requests.get('http://120.27.34.24:9001', auth=HTTPBasicAuth('user', '123')) //传入用户名和密码
print(r.status_code)
方法2
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: //超时捕获这个异常
print('Timeout')
except ConnectionError: //网络有问题时捕获这个异常
print('Connection error')
except RequestException:
print('Error')
参考
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