APIView中的dispatch

（1）dispatch方法详解----封装原有的request对象

（原request中的方法和属性均可直接在封装后的request中调用，或者使用request._request也可，如：request.user == request._request.user

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
    #1.对原来的request进行进一步封装
    request = self.initialize_request(request, *args, **kwargs)
    self.request = request#(2)request已经是经过进一步封装的
    self.headers = self.default_response_headers  # deprecate?
 
    try:
#2.增加对request的调用
        self.initial(request, *args, **kwargs)#(3)比View中多的执行的方法，使用封装过后的request进行调用
 
        # 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)#(4)对原响应对象进行进一步封装
    return self.response

（2）initialize_request对原生request进行封装　　

def initialize_request(self, request, *args, **kwargs):
    """
    Returns the initial request object.
    """
    parser_context = self.get_parser_context(request)
 
    return Request(
        request,#（1-1）原来的request
        parsers=self.get_parsers(),#(1-2)[反序列化方式列表]
        authenticators=self.get_authenticators(),#(1-3)实例化调用了rest_framework配置文件[中间件的认证类列表]---[BasicAuthentication对象,SessionAuthentication对象]
        negotiator=self.get_content_negotiator(),
        parser_context=parser_context
    )

（3）self.initial详解----认证+权限+节流+版本控制　　

self.initial(request, *args, **kwargs)#(3)比View中多的执行的方法，使用封装过后的request进行调用

def initial(self, request, *args, **kwargs):
    """
    Runs anything that needs to occur prior to calling the method handler.
    """
    self.format_kwarg = self.get_format_suffix(**kwargs)

    # Perform content negotiation and store the accepted info on the request
    neg = self.perform_content_negotiation(request)
    request.accepted_renderer, request.accepted_media_type = neg

    # Determine the API version, if versioning is in use.（3-0）api版本的获取
    version, scheme = self.determine_version(request, *args, **kwargs)
    request.version, request.versioning_scheme = version, scheme#版本号和版本处理对象

    # Ensure that the incoming request is permitted
    self.perform_authentication(request)#（3-1）进行认证是否登录
    self.check_permissions(request)#（3-2）权限组件
    self.check_throttles(request)#频率组件