python爬蟲―requests庫的用法

requests是python實現(xiàn)的簡單易用的HTTP庫，使用起來比urllib簡潔很多，requests 允許你發(fā)送 HTTP/1.1 請求。指定 URL并添加查詢url字符串即可開始爬取網(wǎng)頁信息等操作

因為是第三方庫，所以使用前需要cmd安裝

pip install requests

安裝完成后import一下，正常則說明可以開始使用了

基本用法：

requests.get()用于請求目標(biāo)網(wǎng)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(tài)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(wǎng)頁源碼
print(response.content) #以字節(jié)流形式打印

以打印狀態(tài)碼為例，運(yùn)行結(jié)果：

狀態(tài)碼：200，證明請求目標(biāo)網(wǎng)站正常

若狀態(tài)碼為403一般是目標(biāo)存有防火墻，觸發(fā)了反爬策略被限制了IP

各種請求方式：

import requests
requests.get('http://www.baidu.com')
requests.post('http://www.baidu.com')
requests.put('http://www.baidu.com')
requests.delete('http://www.baidu.com')
requests.head('http://www.baidu.com')
requests.options('http://www.baidu.com')

基本的get請求

import requests
response = requests.get('http://www.baidu.com')
print(response.text)

帶參數(shù)的GET請求：

第一種直接將參數(shù)放在url內(nèi)

import requests
response = requests.get("https://www.crrcgo.cc/admin/crr_supplier.html?params=1")
print(response.text)

另一種先將參數(shù)填寫在data中，發(fā)起請求時將params參數(shù)指定為data

import requests
data = {
  'params': '1',
}
response = requests.get('https://www.crrcgo.cc/admin/crr_supplier.html?', params=data)
print(response.text)

基本POST請求：

import requests
response = requests.post('http://baidu.com')

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()))

簡單保存一個二進(jìn)制文件

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)

為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)

此方法可以有效地避開防火墻的檢測，隱藏自己身份

使用代理

同添加headers方法一樣，代理參數(shù)也是一個dict這里使用requests庫爬取了IP代理網(wǎng)站的IP與端口和類型。因為是免費(fèi)的，使用的代理地址很快就失效了。

復(fù)制代碼

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.baidu.com'
  get_ipport(get_html(url))

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)

會話維持

import requests
session = requests.Session()
session.get('https://www.crrcgo.cc/admin/crr_supplier.html')
response = session.get('https://www.crrcgo.cc/admin/')
print(response.text)

證書驗證設(shè)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(shè)為FALSE
print(response.status_code)

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

使用try…except來捕獲異常

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')

總結(jié)

本篇文章就到這里了，希望能夠給你帶來幫助，也希望您能夠多多關(guān)注服務(wù)器之家的更多內(nèi)容!

原文鏈接：https://blog.csdn.net/liver100day/article/details/121263281