源码地址：https://github.com/django/django
请求流
代码语言：javascript复制Socketserver.py#StreamRequestHandler -> http/server.py#BaseHTTPRequestHandler -> wsgiref/simple_server.py#WSGIRequestHandler -> django/core/servers/basehttp.py#WSGIRequestHandler：此时就进入到django库中了，那么接下来分析具体的流程。
Django处理逻辑
代码入口：django/core/servers/basehttp.py#WSGIRequestHandler.handle()
代码语言：javascript复制def handle(self):
self.close_connection = True
self.handle_one_request()
while not self.close_connection:
self.handle_one_request()
try:
self.connection.shutdown(socket.SHUT_WR)
except (socket.error, AttributeError):
pass这里很简单，就是处理一个请求，我们进入具体的处理函数：
代码语言：javascript复制def handle_one_request(self):
"""Copy of WSGIRequestHandler.handle() but with different ServerHandler"""
self.raw_requestline = self.rfile.readline(65537)
if len(self.raw_requestline) > 65536:
self.requestline = ''
self.request_version = ''
self.command = ''
self.send_error(414)
return
if not self.parse_request(): # An error code has been sent, just exit
return
handler = ServerHandler(
self.rfile, self.wfile, self.get_stderr(), self.get_environ()
)
handler.request_handler = self # backpointer for logging & connection closing
handler.run(self.server.get_app())注意这里的get_app，就是wsgi规范中定义的application，在这里就是StaticFilesHandler，run方法里面实际就是调用了改app对象：
代码语言：javascript复制try:
self.setup_environ()
self.result = application(self.environ, self.start_response)
self.finish_response()
except (ConnectionAbortedError, BrokenPipeError, ConnectionResetError):
# We expect the client to close the connection abruptly from time
# to time.
return在python中，第一个可调用对象进行调用，实际上就是执行其__call__方法：
代码语言：javascript复制def __call__(self, environ, start_response):
if not self._should_handle(get_path_info(environ)):
return self.application(environ, start_response)
return super().__call__(environ, start_response)这里可以看到，又是调用了其自己管理的app，也就是委托WSGIHandler这个app进行处理，同样的，也是执行的其__call__方法：
代码语言：javascript复制def __call__(self, environ, start_response):
set_script_prefix(get_script_name(environ))
signals.request_started.send(sender=self.__class__, environ=environ)
request = self.request_class(environ)
response = self.get_response(request)
response._handler_class = self.__class__
status = '%d %s' % (response.status_code, response.reason_phrase)
response_headers = [
*response.items(),
*(('Set-Cookie', c.output(header='')) for c in response.cookies.values()),
]
start_response(status, response_headers)
if getattr(response, 'file_to_stream', None) is not None and environ.get('wsgi.file_wrapper'):
response = environ['wsgi.file_wrapper'](response.file_to_stream)
return response可以看到，这里将wsgi规范中的environ模型转换成了django自身的request模型，然后再传下去进行处理：
代码语言：javascript复制def get_response(self, request):
"""Return an HttpResponse object for the given HttpRequest."""
# Setup default url resolver for this thread
set_urlconf(settings.ROOT_URLCONF)
response = self._middleware_chain(request)
response._closable_objects.append(request)
if response.status_code >= 400:
log_response(
'%s: %s', response.reason_phrase, request.path,
response=response,
request=request,
)
return response这里又调用了中间件链来处理请求，因为在wsgi的流程中，一个请求从请求入口到结果返回，中间会经过一系列的中间件过程，这些中间件实际上也是一个个的app
然后进入到django/core/handlers/base.py的_get_response（）中：
代码语言：javascript复制def _get_response(self, request):
"""
Resolve and call the view, then apply view, exception, and
template_response middleware. This method is everything that happens
inside the request/response middleware.
"""
response = None
if hasattr(request, 'urlconf'):
urlconf = request.urlconf
set_urlconf(urlconf)
resolver = get_resolver(urlconf)
else:
resolver = get_resolver()
resolver_match = resolver.resolve(request.path_info)
callback, callback_args, callback_kwargs = resolver_match
request.resolver_match = resolver_match
# Apply view middleware
for middleware_method in self._view_middleware:
response = middleware_method(request, callback, callback_args, callback_kwargs)
if response:
break
if response is None:
wrapped_callback = self.make_view_atomic(callback)
try:
response = wrapped_callback(request, *callback_args, **callback_kwargs)
except Exception as e:
response = self.process_exception_by_middleware(e, request)继续跟踪代码，最后我们会发现进入到了django/views/generic/base.py的as_view处理中：
代码语言：javascript复制@classonlymethod
def as_view(cls, **initkwargs):
"""Main entry point for a request-response process."""
for key in initkwargs:
if key in cls.http_method_names:
raise TypeError("You tried to pass in the %s method name as a "
"keyword argument to %s(). Don't do that."
% (key, cls.__name__))
if not hasattr(cls, key):
raise TypeError("%s() received an invalid keyword %r. as_view "
"only accepts arguments that are already "
"attributes of the class." % (cls.__name__, key))
def view(request, *args, **kwargs):
self = cls(**initkwargs)
if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get
self.setup(request, *args, **kwargs)
if not hasattr(self, 'request'):
raise AttributeError(
"%s instance has no 'request' attribute. Did you override "
"setup() and forget to call super()?" % cls.__name__
)
return self.dispatch(request, *args, **kwargs)
view.view_class = cls
view.view_initkwargs = initkwargs
# take name and docstring from class
update_wrapper(view, cls, updated=())
# and possible attributes set by decorators
# like csrf_exempt from dispatch
update_wrapper(view, cls.dispatch, assigned=())
return view这里的as_view也就是我们在view控制类中经常使用到的，然后他通过一个分发器对请求进行处理：
代码语言：javascript复制def dispatch(self, request, *args, **kwargs):
"""
`.dispatch()` is pretty much the same as Django's regular dispatch,
but with extra hooks for startup, finalize, and exception handling.
"""
self.args = args
self.kwargs = kwargs
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate?
try:
self.initial(request, *args, **kwargs)
# Get the appropriate handler method
if request.method.lower() in self.http_method_names:
handler = getattr(self, request.method.lower(),
self.http_method_not_allowed)
else:
handler = self.http_method_not_allowed
response = handler(request, *args, **kwargs)
except Exception as exc:
response = self.handle_exception(exc)
self.response = self.finalize_response(request, response, *args, **kwargs)
return self.response可以看到，这里通过请求的类型（get、post等）反射得到view类的具体方法，然后执行，最后就到了我们自己view类的具体方法中了。
