python爬蟲---requests庫的用法

requests是python實現的簡單易用的HTTP庫，使用起來比urllib簡潔不少

由於是第三方庫，因此使用前須要cmd安裝

pip install requests

安裝完成後import一下，正常則說明能夠開始使用了。

基本用法：

requests.get()用於請求目標網站，類型是一個HTTPresponse類型

import requests response = requests.get('http://www.baidu.com')
print(response.status_code) # 打印狀態碼
print(response.url) # 打印請求url
print(response.headers) # 打印頭信息
print(response.cookies) # 打印cookie信息 print(response.text)  #以文本形式打印網頁源碼
print(response.content) #以字節流形式打印

運行結果：

狀態碼：200

url：www.baidu.com

headers信息

 

 

 各類請求方式：

import requests requests.get('http://httpbin.org/get') 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')

 

基本的get請求

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

結果

 

 

 

帶參數的GET請求：

第一種直接將參數放在url內

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

結果

另外一種先將參數填寫在dict中，發起請求時params參數指定爲dict

import requests data = { 'name': 'tom', 'age': 20 } response = requests.get('http://httpbin.org/get', params=data) print(response.text)

結果同上

 

解析json

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

結果

 

簡單保存一個二進制文件

二進制內容爲response.content

import requests response = requests.get('http://img.ivsky.com/img/tupian/pre/201708/30/kekeersitao-002.jpg') b = response.content with open('F://fengjing.jpg','wb') as f: f.write(b)

 

爲你的請求添加頭信息

import requests

heads = {}
heads['User-Agent'] = 'Mozilla/5.0 ' \
                          '(Macintosh; U; Intel Mac OS X 10_6_8; en-us) AppleWebKit/534.50 ' \
                          '(KHTML, like Gecko) Version/5.1 Safari/534.50'

 response = requests.get('http://www.baidu.com',headers=headers)

 

使用代理

同添加headers方法，代理參數也要是一個dict

這裏使用requests庫爬取了IP代理網站的IP與端口和類型

由於是免費的，使用的代理地址很快就失效了。

import requests import re def get_html(url): proxy = { 'http': '120.25.253.234:812',
        'https' '163.125.222.244:8123' } heads = {} heads['User-Agent'] = 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.221 Safari/537.36 SE 2.X MetaSr 1.0' req = requests.get(url, headers=heads,proxies=proxy) html = req.text return html def get_ipport(html): regex = r'<td data-title="IP">(.+)</td>' iplist = re.findall(regex, html) regex2 = '<td data-title="PORT">(.+)</td>' portlist = re.findall(regex2, html) regex3 = r'<td data-title="類型">(.+)</td>' typelist = re.findall(regex3, html) sumray = [] for i in iplist: for p in portlist: for t in typelist: pass
            pass a = t+','+i + ':' + p sumray.append(a) print('高匿代理') print(sumray) if __name__ == '__main__': url = 'http://www.kuaidaili.com/free/' get_ipport(get_html(url))

結果：

 

 

基本POST請求：

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

 

 獲取cookie

#獲取cookie
import requests response = requests.get('http://www.baidu.com') print(response.cookies) print(type(response.cookies)) for k,v in response.cookies.items(): print(k+':'+v)

結果：

 

 

會話維持

import requests session = requests.Session() session.get('http://httpbin.org/cookies/set/number/12345') response = session.get('http://httpbin.org/cookies') print(response.text)

結果：

 

證書驗證設置

import requests from requests.packages import urllib3 urllib3.disable_warnings() #從urllib3中消除警告
response = requests.get('https://www.12306.cn',verify=False)  #證書驗證設爲FALSE
print(response.status_code)

打印結果：200

 

超時異常捕獲

import requests from requests.exceptions import ReadTimeout try: res = requests.get('http://httpbin.org', timeout=0.1) print(res.status_code) except ReadTimeout: print(timeout)

 

異常處理

在你不肯定會發生什麼錯誤時，儘可能使用try...except來捕獲異常

全部的requests exception：

Exceptions

import requests from requests.exceptions import ReadTimeout,HTTPError,RequestException try: response = requests.get('http://www.baidu.com',timeout=0.5) print(response.status_code) except ReadTimeout: print('timeout') except HTTPError: print('httperror') except RequestException: print('reqerror')