数据获取--爬虫-3(Request库)

Request库使用教程


相比于urllib更加简便易用的HTTP库。

Requests

GET请求:只需要向requests.get()方法中传入相应的url即可以实现GET请求并获得Response。POST请求使用requests.post()方法实现代码如下:

#GET请求
import requests

response = requests.get('https://www.baidu.com/')
print(response)
#POST请求
import requests

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

requests库中提供更简便的传入参数的方法,将一个字典形式的参数传递给params参数就能直接实现在url中添加参数。POST请求的DataForm也可以直接这样设置具体代码如下:

# GET请求
import requests

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

# POST请求
import requests

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

设置headers:直接将headers信息传入get()函数相应的参数中即可,POST请求headers设置方法相同(相应代码见上一个代码块)代码如下:

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)

Response

  1. json解析:requests库提供了简单易用的json解析方式,如果Response返回为json格式,.json()方法能直接将Request保存成json格式,这与使用json.loads()函数效果完全一样。代码如下:

    import requests
    import json
    
    response = requests.get("http://httpbin.org/get")
    print(type(response.text))
    print(response.json())#使用json方法解析
    print(json.loads(response.text))#使用loads方法转化为json,与上一行比较返回结果一样。
    print(type(response.json()))
    
  2. 获取二进制数据:想要从网页获取图片和视频等数据需要使用.content方法,然后将使用文件保存操作将内容保存到本地。代码如下:

    import requests
    
    response = requests.get("https://github.com/favicon.ico")#通过传入URL下载图片
    print(type(response.text), type(response.content))
    print(response.text)
    print(response.content)#文件的二进制编码,与urllib库一样。
    
    with open('favicon.ico', 'wb') as f:#保存文件
        f.write(response.content)
        f.close()
    
  3. 状态码:使用.status_code()方法可以获得服务器返回的状态码,每一个状态码都对应一种状态,对应情况见下表:

    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'),
    

可以通过这些状态码获取服务器状态:

import requests

response = requests.get('http://www.jianshu.com/hello.html')
print(type(response.status_code), response.status_code)
exit() if not response.status_code == requests.codes.not_found else print('404 Not Found')#方法一:使用状态码对应的信息进行验证。

response = requests.get('http://www.jianshu.com')
print(type(response.status_code), response.status_code)
exit() if not response.status_code == 200 else print('Request Successfully')
#使用状态码值进行验证
#其实我不理解这两种方法的语法结构
#我看了一下官方文档,如果发送了一个错误请求(一个 4XX 客户端错误,或者 5XX 服务器错误响应),我们可以通过 Response.raise_for_status() 来抛出异常:

import requests
bad_r = requests.get('http://www.jianshu.com')
print(bad_r.status_code)
bad_r.raise_for_status()

高级操作

  1. 文件上传

    import requests
    #用open方法打开图片,储存到file中,保存到字典files中。
    files = {'file': open('favicon.ico', 'rb')}
    #发送Request时将其传入对应的参数中
    response = requests.post("http://httpbin.org/post", files=files)
    print(response.text)#获取并打印结果
    
  2. cookies:requests库中提供了.cookies方法获取cookies,得到的cookies为json格式。

    import requests
    
    response = requests.get('http://www.jianshu.com')
    print(type(response.cookies), response.cookies)
    print(response.cookies)#可以直接导出cookie不需要先声明CookieJar类,更简单。
    for key, value in response.cookies.items():#打印json格式的cookies
        print(key + '=' + value)
    

    通过cookies可以实现模拟登陆, 需要注意的是,模拟对话必须在同一次调用进行 如果需要多次调用,requests中提供了Session类,实现在同一次对话中发起多次请求。

    import requests
    
    url = 'http://httpbin.org/cookies'
    cookies = dict(cookies_are='working')#设置cookies
    #一次请求并获取反馈
    r = requests.get(url, cookies=cookies)
    print(r.text)
    #多次请求
    s = requests.Session()
    s.get(url, cookies=cookies)
    response = s.get(url)
    print(response.text)
    
  3. 证书验证:在爬去HTTPS网站时,浏览器会首先检测证书是否合法,如果证书有问题会直接抛出SSLError,程序会终止。为了避免此类情况,可以选择不验证,不验证证书会发出警告,可以使用代码消除,代码如下:

    import requests
    #消除警告操作
    from requests.packages import urllib3
    urllib3.disable_warnings()
    #verify参数设置为False,不验证
    response = requests.get('https://www.12306.cn', verify=False)
    print(response.status_code)
    
  4. 代理设置:将代理信息保存在字典中,并传入相应参数中即可,代码如下:

    import requests
    #http代理
    proxies = {
        "http": "http://user:password@127.0.0.1:9743/",
    "https": "https://127.0.0.1:9743",
    }#如果代理有密码,可以在域名前进行设置,用冒号分割。
    proxies = {
        'http': 'socks5://127.0.0.1:9742',
        'https': 'socks5://127.0.0.1:9742'
    }#如果使用SSR代理,需要提前安装'requests[socks]',如上设置即可
    response = requests.get("https://www.taobao.com", proxies=proxies)
    print(response.status_code)
    
  5. 超时处理:为访问指定时间, 为了捕获Timeout异常,需要找到Timeout属于哪一个类。

    import requests
    from requests.exceptions import ReadTimeout
    try:
        response = requests.get("http://httpbin.org/get", timeout = 0.5)
        print(response.status_code)
    except ReadTimeout:#Timeout属于ReadTimeout异常类
        print('Timeout')
    
  6. 认证设置:有些网站 访问时 会就会有认证,不通过验证无法打开页面那种。在auth中传入元组类型用户名和密码即可。

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

    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')
    
  8. 其他功能:

    print(type(response.url), response.url)
    print(type(response.history), response.history)
    print(response.text)#与urllib库中的response.read()功能相同
    
    
原文地址:https://www.cnblogs.com/lizhe-Ning/p/11710617.html