本文主要是对 requests 的 for human 结构的部分进行简单分析，对于里面具体的功能实现（比如cookies如何存储，http相关对接）没有深入研究。
1 对于requests主要模块说明：
1.1 __init__.py: 写入了requests的各种方法，可以直接调用
1.2 api.py: 定义了requests 的请求的各种方法（get, post, put, delete...)
1.3 session.py: 主要定义了Session类，里面封装这各种session的具体请求方法(Session.request()..)
1.4 model.py: 定义了各种模型（Request, Response)
1.5 utils.py: 定义了中途需要用的各种方法
2 requests的具体请求过程
html = requests.get('https://www.baidu.com', headers=headers).text html2 = requests.Session().get('https://www.xxx.com', coookies=cookies).text
2.1 requests or session
不管是 requests.get 还是 requests.Session.get 他都会先去 调用调用 session.request(method=method, url=url, **kwargs) 方法
with sessions.Session() as session: return session.request(method=method, url=url, **kwargs)
***此处补一句， 定义方法时候传入**kwargs这样类型的参数，很方便后面对象或方法接收参数。***
2.2 session.request 过程
所以现在我们来看 session.request 这个方法
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. ...""" # 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
2.3 Request类
首先将接收到的各种参数（headers, cookies,...）传入Request类进行封装
class Request(RequestHooksMixin): def __init__(self, method=None, url=None, headers=None, files=None, data=None, params=None, auth=None, cookies=None, hooks=None, json=None): # Default empty dicts for dict params. data = [] if data is None else data files = [] if files is None else files headers = {} if headers is None else headers params = {} if params is None else params hooks = {} if hooks is None else hooks self.hooks = default_hooks() for (k, v) in list(hooks.items()): self.register_hook(event=k, hook=v) self.method = method self.url = url self.headers = headers self.files = files self.data = data self.json = json self.params = params self.auth = auth self.cookies = cookies # ...
2.4 对request和传入的参数进行处理
然后将封装好的对象传入 prepare_request(self, request) 方法
def prepare_request(self, request): cookies = request.cookies or {} # Bootstrap CookieJar. if not isinstance(cookies, cookielib.CookieJar): cookies = cookiejar_from_dict(cookies) # Merge with session cookies merged_cookies = merge_cookies( merge_cookies(RequestsCookieJar(), self.cookies), cookies) # Set environment's basic authentication if not explicitly set. auth = request.auth if self.trust_env and not auth and not self.auth: auth = get_netrc_auth(request.url) p = PreparedRequest() p.prepare( method=request.method.upper(), url=request.url, files=request.files, data=request.data, json=request.json, headers=merge_setting(request.headers, self.headers, dict_class=CaseInsensitiveDict), params=merge_setting(request.params, self.params), auth=merge_setting(auth, self.auth), cookies=merged_cookies, hooks=merge_hooks(request.hooks, self.hooks), ) return p
该方法主要是对传入个各种参数（headers, cookies,...）进行相应的处理以便后续调用，
这里他先将cookies进行了处理，然后对所有传入的参数进行相应处理，调用PrepareRequest.prepare 方法进行处理
def prepare(self, method=None, url=None, headers=None, files=None, data=None, params=None, auth=None, cookies=None, hooks=None, json=None): """Prepares the entire request with the given parameters.""" self.prepare_method(method) self.prepare_url(url, params) self.prepare_headers(headers) self.prepare_cookies(cookies) self.prepare_body(data, files, json) self.prepare_auth(auth, url) # Note that prepare_auth must be last to enable authentication schemes # such as OAuth to work on a fully prepared request. # This MUST go after prepare_auth. Authenticators could add a hook self.prepare_hooks(hooks)
可以看出，每个具体的请求参数都有对应的参数进行处理。
2.5 发送得到response
request请求对象设计好后，send(request)，得到 response