python爬蟲之requests的基本使用
阿新 • • 發佈：2019-01-04
簡介
Requests是用python語言基於urllib編寫的，採用的是Apache2 Licensed開源協議的HTTP庫，Requests它會比urllib更加方便，可以節約我們大量的工作。
一、安裝
pip快速安裝pip install requests
二、使用
1、先上一串程式碼
import requests
response = requests.get("https://www.baidu.com")
print(type(response))
print(response.status_code)
print(type(response.text))
#獲得響應頭內容 response.text返回的是Unicode格式，通常需要轉換為utf-8格式，否則就是亂碼。response.content是二進位制模式，可以下載視訊之類的，如果想看的話需要decode成utf-8格式。
不管是通過response.content.decode(“utf-8)的方式還是通過response.encoding=”utf-8”的方式都可以避免亂碼的問題發生
2、一大推請求方式
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" 基本GET:
import requests
url = 'https://www.baidu.com/'
response = requests.get(url)
print(response.text)帶引數的GET請求：
下面提交的資料是往這個地址傳送data裡面的資料。
import requests
url = 'http://httpbin.org/get'
data = {
'name':'zhangsan',
'age':'25'
}
response = requests.get(url,params=data)
print(response.url)
print(response.text)Json資料：
從下面的資料中我們可以得出，如果結果：
1、requests中response.json()方法等同於json.loads（response.text）方法
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())
print(response.json()['data'])獲取二進位制資料
在上面提到了response.content，這樣獲取的資料是二進位制資料，同樣的這個方法也可以用於下載圖片以及視訊資源
新增header
首先說，為什麼要加header（頭部資訊）呢？例如下面，我們試圖訪問知乎的登入頁面（當然大家都你要是不登入知乎，就看不到裡面的內容），我們試試不加header資訊會報什麼錯。
import requests
url = 'https://www.zhihu.com/'
response = requests.get(url)
response.encoding = "utf-8"
print(response.text)結果：
提示發生內部伺服器錯誤（也就說你連知乎登入頁面的html都下載不下來）。
<html><body><h1>500 Server Error</h1>
An internal server error occured.
</body></html>如果想訪問就必須得加headers資訊。
import requests
url = 'https://www.zhihu.com/'
headers = {
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36'
}
response = requests.get(url,headers=headers)
print(response.text)基本post請求：
通過post把資料提交到url地址，等同於一字典的形式提交form表單裡面的資料
import requests
url = 'http://httpbin.org/post'
data = {
'name':'jack',
'age':'23'
}
response = requests.post(url,data=data)
print(response.text)結果：
{
"args": {},
"data": "",
"files": {},
"form": {
"age": "23",
"name": "jack"
},
"headers": {
"Accept": "*/*",
"Accept-Encoding": "gzip, deflate",
"Connection": "close",
"Content-Length": "16",
"Content-Type": "application/x-www-form-urlencoded",
"Host": "httpbin.org",
"User-Agent": "python-requests/2.13.0"
},
"json": null,
"origin": "118.144.137.95",
"url": "http://httpbin.org/post"
}響應：
import requests
#allow_redirects=False#設定這個屬性為False則是不允許重定向，反之可以重定向
response = requests.get("http://www.baidu.com",allow_redirects=False)
#列印請求頁面的狀態（狀態碼）
print(type(response.status_code),response.status_code)
#列印請求網址的headers所有資訊
print(type(response.headers),response.headers)
#列印請求網址的cookies資訊
print(type(response.cookies),response.cookies)
#列印請求網址的地址
print(type(response.url),response.url)
#列印請求的歷史記錄（以列表的形式顯示）
print(type(response.history),response.history)
內建的狀態碼：
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'),import requests
response = requests.get('http://www.jianshu.com/404.html')
# 使用request內建的字母判斷狀態碼
#如果response返回的狀態碼是非正常的就返回404錯誤
if response.status_code != requests.codes.ok:
print('404')
#如果頁面返回的狀態碼是200，就列印下面的狀態
response = requests.get('http://www.jianshu.com')
if response.status_code == 200:
print('200')request的高階操作
檔案上傳
import requests
url = "http://httpbin.org/post"
files= {"files":open("test.jpg","rb")}
response = requests.post(url,files=files)
print(response.text)結果：
獲取cookie
import requests
response = requests.get('https://www.baidu.com')
print(response.cookies)
for key,value in response.cookies.items():
print(key,'==',value)會話維持
cookie的一個作用就是可以用於模擬登陸，做會話維持
import requests
session = requests.session()
session.get('http://httpbin.org/cookies/set/number/12456')
response = session.get('http://httpbin.org/cookies')
print(response.text)證書驗證
1、無證書訪問
import requests
response = requests.get('https://www.12306.cn')
# 在請求https時，request會進行證書的驗證，如果驗證失敗則會丟擲異常
print(response.status_code)報錯：
關閉證書驗證
import requests
# 關閉驗證，但是仍然會報出證書警告
response = requests.get('https://www.12306.cn',verify=False)
print(response.status_code)為了避免這種情況的發生可以通過verify=False，但是這樣是可以訪問到頁面結果
消除驗證證書的警報
from requests.packages import urllib3
import requests
urllib3.disable_warnings()
response = requests.get('https://www.12306.cn',verify=False)
print(response.status_code)手動設定證書
import requests
response = requests.get('https://www.12306.cn', cert=('/path/server.crt', '/path/key'))
print(response.status_code)代理設定
1、設定普通代理
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、設定使用者名稱和密碼代理
設定socks代理
安裝socks模組 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)超時設定
通過timeout引數可以設定超時的時間
import requests
from requests.exceptions import ReadTimeout
try:
# 設定必須在500ms內收到響應，不然或丟擲ReadTimeout異常
response = requests.get("http://httpbin.org/get", timeout=0.5)
print(response.status_code)
except ReadTimeout:
print('Timeout')認證設定
如果碰到需要認證的網站可以通過requests.auth模組實現
import requests
from requests.auth import HTTPBasicAuth
<br>#方法一
r = requests.get('http://120.27.34.24:9001', auth=HTTPBasicAuth('user', '123'))<br>
#方法二<br>r = requests.get('http://120.27.34.24:9001', auth=('user', '123'))
print(r.status_code)異常處理
所有的異常都是在requests.excepitons中
從原始碼我們可以看出
RequestException繼承IOError,
HTTPError，ConnectionError,Timeout繼承RequestionException，ProxyError，SSLError繼承ConnectionError，
ReadTimeout繼承Timeout異常
通過下面的例子進行簡單的演示
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')首先被捕捉的異常是timeout,當把網路斷掉的haul就會捕捉到ConnectionError，如果前面異常都沒有捕捉到，最後也可以通過RequestExctption捕捉到
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