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python爬虫---requests库的用法

时间:2017-11-22 22:49:58      阅读:225      评论:0      收藏:0      [点我收藏+]

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 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

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 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

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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

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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

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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:

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基本POST请求:

import requests

data = {name:tom,age:22}

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

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 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:

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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:

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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)

 

 

 

python爬虫---requests库的用法

原文:http://www.cnblogs.com/mzc1997/p/7813801.html

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