• 4.爬虫 requests库讲解 GET请求 POST请求 响应


    requests库相比于urllib库更好用!!!

    0.各种请求方式

    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')

    *http://httpbin.org是一个http请求验证网站!

    1.GET请求

    • 带参数的get请求(两种方式是等效的)
    import requests
    
    response = requests.get("http://httpbin.org/get?name=germey&age=22")
    print(response.text)
    
    ########################
    
    import requests
    
    data = {
        'name': 'germey',
        'age': 22
    }
    response = requests.get("http://httpbin.org/get", params=data)
    print(response.text)

    输出结果如下:

    {
      "args": {
        "age": "22", 
        "name": "germey"
      }, 
      "headers": {
        "Accept": "*/*", 
        "Accept-Encoding": "gzip, deflate", 
        "Host": "httpbin.org", 
        "User-Agent": "python-requests/2.18.4"
      }, 
      "origin": "182.148.156.45, 182.148.156.45", 
      "url": "https://httpbin.org/get?name=germey&age=22"
    }
    

    * params=data 对于get请求 添加附加的格外的信息,这个信息一般用字典来存储,可见返回的结果中args字段.

    • 解析json
    import requests
    import json
    
    response = requests.get("http://httpbin.org/get")
    print(type(response.text))
    print(response.json())
    print(json.loads(response.text))
    print(type(response.json()))

    输出结果如下:

    <class 'str'>
    {'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.18.4'}, 'origin': '182.148.156.45, 182.148.156.45', 'url': 'https://httpbin.org/get'}
    {'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.18.4'}, 'origin': '182.148.156.45, 182.148.156.45', 'url': 'https://httpbin.org/get'}
    <class 'dict'>
    

    *网页返回的类型是str类型,但是有的很特殊,返回的是JSON格式的字符串.json()将JSON格式的字符串转换为字典。

    *可以看到response.json()和json.loads(response.text)打印出来的结果是一样的!

    *倘若网页返回的结果不是JSON格式的,便会出现解析错误,抛出json.decoder.JSONDecodeError的异常。

    • 获取二进制数据
    import requests
    
    response = requests.get("https://github.com/favicon.ico")
    print(type(response.text), type(response.content))
    print(response.text)
    print(response.content)

    """
    #抓取并保存二进制数据(图片、视频、音频等文件)
    with open('文件名称','wb') as f:
      f.write(r.content)
    """

    *图标地址一般都放在网络根目录下,名称为favicon.ico

    *获取文本数据:response.text

    *获取图片等二进制数据:response.content

    • 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)

    2.POST请求

    • 带参数POST请求
    import requests
    
    data = {'name': 'germey', 'age': '22'}
    response = requests.post("http://httpbin.org/post", params=data)print(response.text)
    • 添加headers
    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", params=data, headers=headers)
    print(response.text)
    print(response.json())

    输出结果如下:

    {
      "args": {
        "age": "22", 
        "name": "germey"
      }, 
      "data": "", 
      "files": {}, 
      "form": {}, 
      "headers": {
        "Accept": "*/*", 
        "Accept-Encoding": "gzip, deflate", 
        "Content-Length": "0", 
        "Host": "httpbin.org", 
        "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"
      }, 
      "json": null, 
      "origin": "101.206.170.234, 101.206.170.234", 
      "url": "https://httpbin.org/post?name=germey&age=22"
    }
    
    {'args': {'age': '22', 'name': 'germey'}, 'data': '', 'files': {}, 'form': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Content-Length': '0', 'Host': 'httpbin.org', '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'}, 'json': None, 'origin': '101.206.170.234, 101.206.170.234', 'url': 'https://httpbin.org/post?name=germey&age=22'}

     *可以看到GET和POST方式的带参数的请求和添加headers的方式差不多!

    3.响应

    • reponse属性
    import requests
    
    response = requests.get('http://www.jianshu.com')
    print(type(response.status_code), response.status_code) #状态码
    print(type(response.headers), response.headers) #响应头
    print(type(response.cookies), response.cookies) #cookies值
    print(type(response.url), response.url) #url
    print(type(response.history), response.history) #请求历史

    输出结果如下:

    <class 'int'> 403
    <class 'requests.structures.CaseInsensitiveDict'> {'Server': 'Tengine', 'Content-Type': 'text/html', 'Transfer-Encoding': 'chunked', 'Connection': 'keep-alive', 'Date': 'Tue, 09 Apr 2019 13:14:23 GMT', 'Vary': 'Accept-Encoding', 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains; preload', 'Content-Encoding': 'gzip', 'x-alicdn-da-ups-status': 'endOs,0,403', 'Via': 'cache29.l2cm12-6[17,0], cache8.cn389[77,0]', 'Timing-Allow-Origin': '*', 'EagleId': '7d412b4815548156634056180e'}
    <class 'requests.cookies.RequestsCookieJar'> <RequestsCookieJar[]>
    <class 'str'> https://www.jianshu.com/
    <class 'list'> [<Response [301]>]
    
    • 状态码判断

    下面列出反悔码和相应的查询条件:

    # 信息性状态码
    100: ('continue',),
    101: ('switching_protocols',),
    102: ('processing',),
    103: ('checkpoint',),
    122: ('uri_too_long', 'request_uri_too_long'),
    
    # 成功状态码
    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.重定向
    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.客户端错误
    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.服务端错误
    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'),
    

    状态码用于判断请求是否成功,requests还提供了一个内置的状态码查询对象requests.codes。(两种写法都可以)

    import requests
    
    response = requests.get('http://www.jianshu.com')
    exit() if not response.status_code == requests.codes.ok else print('Request Successfully')
    
    ###################################
    import requests
    
    response = requests.get('http://www.jianshu.com')
    exit() if not response.status_code == 200 else print('Request Successfully')
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  • 原文地址:https://www.cnblogs.com/DC0307/p/10679283.html
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