爬虫值requests库

requests简介

简介

Requests是用python语言基于urllib编写的，采用的是Apache2 Licensed开源协议的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 requests

response = 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':''}

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：

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')

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