• python爬虫---requests库的用法


    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

    复制代码
    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
    复制代码

    运行结果:

    状态码:200

    url:www.baidu.com

    headers信息

     各种请求方式:

    复制代码
    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')
    复制代码

    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

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

    结果同上

    解析json

    复制代码
    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()))
    复制代码

    结果

    简单保存一个二进制文件

    二进制内容为response.content

    复制代码
    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)
    复制代码

    为你的请求添加头信息

    复制代码
    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)
    复制代码

    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。

    复制代码
    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))
    复制代码

    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

    复制代码
    #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)
    复制代码

    结果:

    会话维持

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

    结果:

    证书验证设置

    复制代码
    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
    复制代码

    超时异常捕获

    复制代码
    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)
    复制代码

    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

    复制代码
    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')
    复制代码

     

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  • 原文地址:https://www.cnblogs.com/ExMan/p/10020549.html
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