python爬虫—requests库的用法详解

requests是python实现的简单易用的HTTP库，使用起来比urllib简洁很多

因为是第三方库，所以使用前需要cmd安装

pip install requests

安装完成后import一下，正常则说明可以开始使用了。

基本用法：

requests.get()用于请求目标网站，类型是一个HTTPresponse类型

import requestsresponse = requests.get(\'http://www.baidu.com\')
print(response.status_code) # 打印状态码
print(response.url) # 打印请求url
print(response.headers) # 打印头信息
print(response.cookies) # 打印cookie信息
print(response.text) #以文本形式打印网页源码
print(response.content) #以字节流形式打印

运行结果：

状态码：200

url：www.baidu.com

headers信息

各种请求方式：

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请求

import requests

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

结果

带参数的GET请求：

第一种直接将参数放在url内

import requests

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

结果

另一种先将参数填写在dict中，发起请求时params参数指定为dict

import requests

data = {
  \'name\': \'tom\',
  \'age\': 20
}

response = requests.get(\'http://httpbin.org/get\', params=data)
print(response.text)

结果同上

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()))

结果

简单保存一个二进制文件

二进制内容为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)

为你的请求添加头信息

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，代理参数也要是一个dict

这里使用requests库爬取了IP代理网站的IP与端口和类型

因为是免费的，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=\"类型\">(.+)</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))

结果：

基本POST请求：

import requests

data = {\'name\':\'tom\',\'age\':\'22\'}

response = requests.post(\'http://httpbin.org/post\', data=data)

获取cookie

#获取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)

结果：

会话维持

import requests

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

结果：

证书验证设置

import requests
from requests.packages import urllib3

urllib3.disable_warnings() #从urllib3中消除警告
response = requests.get(\'https://www.12306.cn\',verify=False) #证书验证设为FALSE
print(response.status_code)打印结果：200

超时异常捕获

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)

异常处理

在你不确定会发生什么错误时，尽量使用try…except来捕获异常

所有的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\')

25行代码带你爬取4399小游戏数据

import requests
import parsel
import csv
f = open(\'4399游戏.csv\', mode=\'a\', encoding=\'utf-8-sig\', newline=\'\')

csv_writer = csv.DictWriter(f, fieldnames=[\'游戏地址\', \'游戏名字\'])
csv_writer.writeheader()
for page in range(1, 106):
  url = \'http://www.4399.com/flash_fl/5_{}.htm\'.format(page)
  headers = {
    \'User-Agent\': \'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36\'
  }
  response = requests.get(url=url, headers=headers)
  response.encoding = response.apparent_encoding
  selector = parsel.Selector(response.text)
  lis = selector.css(\'#classic li\')
  for li in lis:
    dit ={}
    data_url = li.css(\'a::attr(href)\').get()
    new_url = \'http://www.4399.com\' + data_url.replace(\'http://\', \'/\')
    dit[\'游戏地址\'] = new_url
    title = li.css(\'img::attr(alt)\').get()
    dit[\'游戏名字\'] = title
    print(new_url, title)
    csv_writer.writerow(dit)
f.close()

到此这篇关于python爬虫—requests库的用法详解的文章就介绍到这了,更多相关python requests库内容请搜索自学编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持自学编程网！