在Flask中，新增路由有兩種方式：（一般情況下都是用第一種方式）

第一種：常見的裝飾器模式

@app.route("/")
def index():
    return "Hello World"

通過這種方式，將rule與檢視函式對應起來

第二種：通過閱讀裝飾器模式新增路由的原始碼發現

def route(self, rule, **options):
    """A decorator that is used to register a view function for a
    given URL rule.  This does the same thing as :meth:`add_url_rule`
    but is intended for decorator usage::

        @app.route('/')
        def index():
            return 'Hello World'

    For more information refer to :ref:`url-route-registrations`.

    :param rule: the URL rule as string
    :param endpoint: the endpoint for the registered URL rule.  Flask
                     itself assumes the name of the view function as
                     endpoint
    :param options: the options to be forwarded to the underlying
                    :class:`~werkzeug.routing.Rule` object.  A change
                    to Werkzeug is handling of method options.  methods
                    is a list of methods this rule should be limited
                    to (``GET``, ``POST`` etc.).  By default a rule
                    just listens for ``GET`` (and implicitly ``HEAD``).
                    Starting with Flask 0.6, ``OPTIONS`` is implicitly
                    added and handled by the standard request handling.
    
 
"""

    def decorator(f):
        endpoint = options.pop("endpoint", None)
        self.add_url_rule(rule, endpoint, f, **options)
        return f

    return decorator

是通過self.add_url_rule這個方式建立起rule與檢視函式的對應關係的，所以可以這樣新增，

def home():
    return "Hello, home!"


app.add_url_rule("/home", endpoint=None, view_func=home)

endpoint:給rule起一個別名，相當於django path路由函式中的name。