【零基础学爬虫】requests库详解

迷南。 2022-04-24 07:18 324阅读 0赞

# 【1】Requests简介 #

*  Requests 是⽤用Python语⾔言编写，基于 urllib，采⽤ Apache2 Licensed 开源协议的 HTTP 库。
 *  它比 urllib 更加⽅便，可以节约我们⼤量的⼯工作，完全满足  
    HTTP 测试需求。
 *  ⼀句话：Requests是Python实现的**简单易用**的HTTP库  
    \#\#\#\#\#Request的安装  
    pip install requests  
    \#Requests实战  
    \#\#\#1.发起HTTP 请求

import requests
    response = requests.get('https://www.baidu.com/')
    print(type(response))
    print(response.status_code)
    print(type(response.text))
    print(response.text)
    print(response.cookies)

### 2.各类请求方式 ###

import requests
    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')

### 2.基本的get请求 ###

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

### 3.带参数GET请求 ###

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

上面这种拼接参数的方式可能不太方便，下面是另外一种带参数get请求发起的方式，与上面是等价的。

import requests
    data = { 
        'name': 'germey',
        'age': 22
    }
    response = requests.get("http://httpbin.org/get", params=data)
    print(response.text)

### 4.解析json ###

import requests
    import json
    response = requests.get("http://httpbin.org/get")
    print(type(response.text))#str格式
    print(response.json())#json格式输出
    print(json.loads(response.text))#和上结果一样
    print(type(response.json()))#json是dict格式，即字典格式

### 5.获取二进制数据 ###

import requests
    response = requests.get("https://github.com/favicon.ico")
    print(type(response.text), type(response.content))#str和bytes格式
    print(response.text)#乱码
    print(response.content)#二进制字节流

保存图片：

import requests
    response = requests.get("https://github.com/favicon.ico")
    with open('favicon.ico', 'wb') as f:
        f.write(response.content)
        f.close()

### 6.添加headers ###

在写爬虫的时候，如果不加headers，可能会服务器拒绝访问，如：

import requests
    response = requests.get("https://www.zhihu.com/explore")
    print(response.text)#response中的状态码是400，错误请求

添加headers

import requests
    headers = { 
        'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36'
    }
    response = requests.get("https://www.zhihu.com/explore", headers=headers)
    print(response.text)#返回正常结果

### 7.基本的post请求 ###

post请求需要用户携带一些数据，典型的就是用户登录

import requests
    data = { 'name': 'germey', 'age': '22'}
    response = requests.post("http://httpbin.org/post", data=data)
    print(response.text)

--------------------

# 【2】response #

### 1.response的主要属性 ###

import requests
    response = requests.get('http://www.jianshu.com')
    print(type(response.status_code), response.status_code)
    print(type(response.headers), response.headers)
    print(type(response.cookies), response.cookies)
    print(type(response.url), response.url)
    print(type(response.history), response.history)

### 2.状态码判断 ###

import requests
    
    response = requests.get('http://www.jianshu.com/hello.html')
    exit() if not response.status_code == requests.codes.not_found else print('404 Not Found')

import requests
    
    response = requests.get('http://www.jianshu.com')
    exit() if not response.status_code == 200 else print('Request Successfully')

### 3.常见的状态码：这也是面试常问的问题 ###

> 100: (‘continue’,),  
> 101: (‘switching\_protocols’,),  
> 102: (‘processing’,),  
> 103: (‘checkpoint’,),  
> 122: (‘uri\_too\_long’, ‘request\_uri\_too\_long’),

> 200: (‘ok’, ‘okay’, ‘all\_ok’, ‘all\_okay’, ‘all\_good’, ‘\\o/’, ‘✓’),  
> 201: (‘created’,),  
> 202: (‘accepted’,),  
> 203: (‘non\_authoritative\_info’, ‘non\_authoritative\_information’),  
> 204: (‘no\_content’,),  
> 205: (‘reset\_content’, ‘reset’),  
> 206: (‘partial\_content’, ‘partial’),  
> 207: (‘multi\_status’, ‘multiple\_status’, ‘multi\_stati’, ‘multiple\_stati’),  
> 208: (‘already\_reported’,),  
> 226: (‘im\_used’,),

Redirection.

> 300: (‘multiple\_choices’,),  
> 301: (‘moved\_permanently’, ‘moved’, ‘\\o-’),  
> 302: (‘found’,),  
> 303: (‘see\_other’, ‘other’),  
> 304: (‘not\_modified’,),  
> 305: (‘use\_proxy’,),  
> 306: (‘switch\_proxy’,),  
> 307: (‘temporary\_redirect’, ‘temporary\_moved’, ‘temporary’),  
> 308: (‘permanent\_redirect’,  
> ‘resume\_incomplete’, ‘resume’,), \# These 2 to be removed in 3.0

Client Error.

> 400: (‘bad\_request’, ‘bad’),  
> 401: (‘unauthorized’,),  
> 402: (‘payment\_required’, ‘payment’),  
> 403: (‘forbidden’,),  
> 404: (‘not\_found’, ‘-o-’),  
> 405: (‘method\_not\_allowed’, ‘not\_allowed’),  
> 406: (‘not\_acceptable’,),  
> 407: (‘proxy\_authentication\_required’, ‘proxy\_auth’, ‘proxy\_authentication’),  
> 408: (‘request\_timeout’, ‘timeout’),  
> 409: (‘conflict’,),  
> 410: (‘gone’,),  
> 411: (‘length\_required’,),  
> 412: (‘precondition\_failed’, ‘precondition’),  
> 413: (‘request\_entity\_too\_large’,),  
> 414: (‘request\_uri\_too\_large’,),  
> 415: (‘unsupported\_media\_type’, ‘unsupported\_media’, ‘media\_type’),  
> 416: (‘requested\_range\_not\_satisfiable’, ‘requested\_range’, ‘range\_not\_satisfiable’),  
> 417: (‘expectation\_failed’,),  
> 418: (‘im\_a\_teapot’, ‘teapot’, ‘i\_am\_a\_teapot’),  
> 421: (‘misdirected\_request’,),  
> 422: (‘unprocessable\_entity’, ‘unprocessable’),  
> 423: (‘locked’,),  
> 424: (‘failed\_dependency’, ‘dependency’),  
> 425: (‘unordered\_collection’, ‘unordered’),  
> 426: (‘upgrade\_required’, ‘upgrade’),  
> 428: (‘precondition\_required’, ‘precondition’),  
> 429: (‘too\_many\_requests’, ‘too\_many’),  
> 431: (‘header\_fields\_too\_large’, ‘fields\_too\_large’),  
> 444: (‘no\_response’, ‘none’),  
> 449: (‘retry\_with’, ‘retry’),  
> 450: (‘blocked\_by\_windows\_parental\_controls’, ‘parental\_controls’),  
> 451: (‘unavailable\_for\_legal\_reasons’, ‘legal\_reasons’),  
> 499: (‘client\_closed\_request’,),

Server Error.

> 500: (‘internal\_server\_error’, ‘server\_error’, ‘/o\\’, ‘✗’),  
> 501: (‘not\_implemented’,),  
> 502: (‘bad\_gateway’,),  
> 503: (‘service\_unavailable’, ‘unavailable’),  
> 504: (‘gateway\_timeout’,),  
> 505: (‘http\_version\_not\_supported’, ‘http\_version’),  
> 506: (‘variant\_also\_negotiates’,),  
> 507: (‘insufficient\_storage’,),  
> 509: (‘bandwidth\_limit\_exceeded’, ‘bandwidth’),  
> 510: (‘not\_extended’,),  
> 511: (‘network\_authentication\_required’, ‘network\_auth’, ‘network\_authentication’),

--------------------

# 【3】高级操作 #

### (1) 文件上传 ###

import requests
    
    files = { 'file': open('favicon.ico', 'rb')}
    response = requests.post("http://httpbin.org/post", files=files)
    print(response.text)

### (2) 获取cookie ###

import requests
    
    response = requests.get("https://www.baidu.com")
    print(response.cookies)
    for key, value in response.cookies.items():
        print(key + '=' + value)

### (3)session可以维持会话信息 ###

import requests
    
    s = requests.Session()
    s.get('http://httpbin.org/cookies/set/number/123456789')#供测试的网址 
    #用session维持会话信息，相对于在一个浏览器中操作
    response = s.get('http://httpbin.org/cookies')
    print(response.text)

输出：

> \{  
> “cookies”: \{  
> “number”: “123456789”  
> \}  
> \}

### (4)证书验证 ###

现在很多网站都需要证书的验证，没有证书会出现“你访问的不是一个私密链接”之类的错误。对于Https协议，直首先会检查证书是否合法，如果证书不合法，则会抛出：SSLError。针对这一点有两种措施：  
下面这种方法：在访问的时候，设置不进行证书的验证，此时返回状态码200，但是依旧会有警告。

import requests
    response = requests.get('https://www.12306.cn')
    print(response.status_code)

消除警告信息：

import requests
    from requests.packages import urllib3
    urllib3.disable_warnings()
    response = requests.get('https://www.12306.cn', verify=False)
    print(response.status_code)

【2】手动指定证书

import requests
    
    response = requests.get('https://www.12306.cn', cert=('/path/server.crt', '/path/key'))
    print(response.status_code)

### (5)代理的设置 ###

import requests
    
    proxies = { 
      "http": "http://127.0.0.1:9743",
      "https": "https://127.0.0.1:9743",
    }
    response = requests.get("https://www.taobao.com", proxies=proxies)
    print(response.status_code)

对于需要用户名和密码的代理

import requests
    
    proxies = { 
        "http": "http://user:password@127.0.0.1:9743/",#指定好用户名和密码
    }
    response = requests.get("https://www.taobao.com", proxies=proxies)
    print(response.status_code)

socks代理：先安装该模块

pip3 install 'requests[socks]'

代理设置

proxies = { 
        'http': 'socks5://127.0.0.1:9742',
        'https': 'socks5://127.0.0.1:9742'
    }
    response = requests.get("https://www.taobao.com", proxies=proxies)
    print(response.status_code)

### (6) 超时设置 ###

import requests
    from requests.exceptions import ReadTimeout
    try:
        response = requests.get("http://httpbin.org/get", timeout = 0.5)
        print(response.status_code)
    except ReadTimeout:

\#\#\#(7)需要登录认证才能访问的网站

import requests
    from requests.auth import HTTPBasicAuth
    
    r = requests.get('http://120.27.34.24:9001', auth=HTTPBasicAuth('user', '123'))
    print(r.status_code)

下面与上面等价：

import requests
    
    r = requests.get('http://120.27.34.24:9001', auth=('user', '123'))
    print(r.status_code)

### (8) 异常处理 ###

import requests
    from requests.exceptions import ReadTimeout, ConnectionError, RequestException
    try:
        response = requests.get("http://httpbin.org/get", timeout = 0.5)
        print(response.status_code)
    except ReadTimeout:
        print('Timeout')
    except ConnectionError:
        print('Connection error')
    except RequestException:
        print('Error')

上面就是request常用的一些方法介绍了

--------------------

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