Python requests库介绍

Python requests库介绍

一、http 基础介绍

通过 requests 发送的请求都将通过以下函数实现

    def request(self, method, url,
            params=None, data=None, headers=None, cookies=None, files=None,
            auth=None, timeout=None, allow_redirects=True, proxies=None,
            hooks=None, stream=None, verify=None, cert=None, json=None):
        """Constructs a :class:`Request <Request>`, prepares it and sends it.
        Returns :class:`Response <Response>` object.

        :param method: method for the new :class:`Request` object.
        :param url: URL for the new :class:`Request` object.
        :param params: (optional) Dictionary or bytes to be sent in the query
            string for the :class:`Request`.
        :param data: (optional) Dictionary, list of tuples, bytes, or file-like
            object to send in the body of the :class:`Request`.
        :param json: (optional) json to send in the body of the
            :class:`Request`.
        :param headers: (optional) Dictionary of HTTP Headers to send with the
            :class:`Request`.
        :param cookies: (optional) Dict or CookieJar object to send with the
            :class:`Request`.
        :param files: (optional) Dictionary of ``'filename': file-like-objects``
            for multipart encoding upload.
        :param auth: (optional) Auth tuple or callable to enable
            Basic/Digest/Custom HTTP Auth.
        :param timeout: (optional) How long to wait for the server to send
            data before giving up, as a float, or a :ref:`(connect timeout,
            read timeout) <timeouts>` tuple.
        :type timeout: float or tuple
        :param allow_redirects: (optional) Set to True by default.
        :type allow_redirects: bool
        :param proxies: (optional) Dictionary mapping protocol or protocol and
            hostname to the URL of the proxy.
        :param stream: (optional) whether to immediately download the response
            content. Defaults to ``False``.
        :param verify: (optional) Either a boolean, in which case it controls whether we verify
            the server's TLS certificate, or a string, in which case it must be a path
            to a CA bundle to use. Defaults to ``True``.
        :param cert: (optional) if String, path to ssl client cert file (.pem).
            If Tuple, ('cert', 'key') pair.
        :rtype: requests.Response
        """
        # Create the Request.
        req = Request(
            method=method.upper(),
            url=url,
            headers=headers,
            files=files,
            data=data or {},
            json=json,
            params=params or {},
            auth=auth,
            cookies=cookies,
            hooks=hooks,
        )
        prep = self.prepare_request(req)

        proxies = proxies or {}

        settings = self.merge_environment_settings(
            prep.url, proxies, stream, verify, cert
        )

        # Send the request.
        send_kwargs = {
            'timeout': timeout,
            'allow_redirects': allow_redirects,
        }
        send_kwargs.update(settings)
        resp = self.send(prep, **send_kwargs)

        return resp

其中的主要参数介绍如下：

• method：请求的方式，get 请求将提交的数据放置在HTTP请求协议头中， post 提交的数据则放在实体数据中

1. GET： 请求指定的页面信息，并返回实体主体。
2. HEAD： 只请求页面的首部。
3. POST： 请求服务器接受所指定的文档作为对所标识的URI的新的从属实体。
4. PUT： 从客户端向服务器传送的数据取代指定的文档的内容。
5. DELETE： 请求服务器删除指定的页面。

• url：访问的网址，比如 www.baidu.com
• params：在 get 方法中介绍
• data：在 post 方法中介绍
• headers：告诉服务器本次请求的一些信息，比如可以接受的媒体类型（text/html，或所有类型*/*），可以接受的编码方式等
• files：将请求信息以文件的方式提供，必须以二进制的方式读取

upload_files = {'file': open('report.xls', 'rb')}
r = requests.post(url, files=upload_files)

• timeout：如果需要获取服务器返回信息，同时不希望无限等待，可以设置超时。超时后将返回异常
• json：在 post 方法中介绍

二、get 方法

def get(url, params=None, **kwargs):
    r"""Sends a GET request.

    :param url: URL for the new :class:`Request` object.
    :param params: (optional) Dictionary, list of tuples or bytes to send
        in the body of the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    kwargs.setdefault('allow_redirects', True)
    return request('get', url, params=params, **kwargs)

参数说明：

• params：将请求信息以字典、元素列表或者字节的方式提供

r = requests.get('https://www.douban.com/search', params={'q': 'python', 'cat': '1001'})
r.url # 实际请求的URL（'https://www.douban.com/search?q=python&cat=1001'）

• 其他参数：见第一部分的介绍

三、post 方式

def post(url, data=None, json=None, **kwargs):
    r"""Sends a POST request.

    :param url: URL for the new :class:`Request` object.
    :param data: (optional) Dictionary, list of tuples, bytes, or file-like
        object to send in the body of the :class:`Request`.
    :param json: (optional) json data to send in the body of the :class:`Request`.
    :param \*\*kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    return request('post', url, data=data, json=json, **kwargs)

参数介绍：

• data：将请求信息以字典、元素列表或者字节的方式提供

r = requests.post('https://accounts.douban.com/login', data={'form_email': 'abc@example.com', 'form_password': '123456'})

• json：将请求信息以json的方式提供，使用默认请求方式 application/x-www-form-urlencoded

params = {'key': 'value'}
r = requests.post(url, json=params) # 内部自动序列化为JSON

• 其他参数：见第一部分的介绍

四、返回值

常用属性介绍：

• text：返回数据的Unicode型数据
• url：实际请求的 url
• encoding：编码方式
• content：返回数据的bytes型也就是二进制的数据
• json()：获取 json 类型的响应数据
• headers：请求的请求头
• cookies['*']：获取 cookies 中的对应信息
• status_code：返回状态信息

五、附录 —— 常见的网页状态码

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'),