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结论：两个都是基于 sessions.Session?发送请求的，区别仅在于前者请求完即刻断开连接（连接只用一次）。后者需要手动断开连接（连接可以反复用）。
requests.get 和session.get 的用法，我们通常是这样的：
# requests直接get
response = requests.get()
#----分割线------------------------------------------
# 先创建一个session对象，然后get
http = requests.Session()
response = http.get(url=url,data=data)
展开requests的源代码，发现requests.get() 和 session.get() 都是基于 sessions.Session() 发送请求的。
requests.request?的源码：
"""
requests.api
~~~~~~~~~~~~
This module implements the Requests API.
:copyright: (c) 2012 by Kenneth Reitz.
:license: Apache2, see LICENSE for more details.
"""
from . import sessions
def request(method, url, **kwargs):
"""Constructs and sends a :class:`Request <Request>`.
:param method: method for the new :class:`Request` object: ``GET``, ``OPTIONS``, ``HEAD``, ``POST``, ``PUT``, ``PATCH``, or ``DELETE``.
:param url: URL for the new :class:`Request` object.
:param params: (optional) Dictionary, list of tuples or bytes to send
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) A JSON serializable Python object 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 ``'name': file-like-objects`` (or ``{'name': file-tuple}``) for multipart encoding upload.
``file-tuple`` can be a 2-tuple ``('filename', fileobj)``, 3-tuple ``('filename', fileobj, 'content_type')``
or a 4-tuple ``('filename', fileobj, 'content_type', custom_headers)``, where ``'content-type'`` is a string
defining the content type of the given file and ``custom_headers`` a dict-like object containing additional headers
to add for the file.
:param auth: (optional) Auth tuple to enable Basic/Digest/Custom HTTP Auth.
:param timeout: (optional) How many seconds 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) Boolean. Enable/disable GET/OPTIONS/POST/PUT/PATCH/DELETE/HEAD redirection. Defaults to ``True``.
:type allow_redirects: bool
:param proxies: (optional) Dictionary mapping protocol to the URL of the proxy.
: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 stream: (optional) if ``False``, the response content will be immediately downloaded.
:param cert: (optional) if String, path to ssl client cert file (.pem). If Tuple, ('cert', 'key') pair.
:return: :class:`Response <Response>` object
:rtype: requests.Response
Usage::
>>> import requests
>>> req = requests.request('GET', 'https://httpbin.org/get')
>>> req
<Response [200]>
"""
# By using the 'with' statement we are sure the session is closed, thus we
# avoid leaving sockets open which can trigger a ResourceWarning in some
# cases, and look like a memory leak in others.
with sessions.Session() as session:
return session.request(method=method, url=url, **kwargs)
requests.Session的源码：
from .sessions import session, Session
即：以下两个写法是完全等效的：
# 写法一
response = request.get()
# 写法二
with request.Session() as http:
response = http.get()
他们的区别仅仅在于requests.get每次都自动关闭连接。而session.get不关闭连接。 [ 类似于with?open() as file? ?会自动关闭，file =?open()?需要手动?]
?另外：
requests.session()?和requests.Session()? 是等效的，但我们应该使用大写字母开头这个，
requests.session() 此方法自1.0.0版起已弃用，仅保留向后兼容性。 新代码应该使用:requests.sessions.Session`创建会话。 这可能会在将来的某个日期被删除。
def session():
"""
Returns a :class:`Session` for context-management.
.. deprecated:: 1.0.0
This method has been deprecated since version 1.0.0 and is only kept for
backwards compatibility. New code should use :class:`~requests.sessions.Session`
to create a session. This may be removed at a future date.
:rtype: Session
"""
return Session()
刚写完发现有一篇内容相似的文章：https://www.cnblogs.com/SunshineKimi/p/11715285.html
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