函数 routers 返回一个 urlpatterns 元组，里面包含了路径名和函数名；在 函数 application 中遍历 urlpatterns 元组，路径存在则返回函数名，不存在则返回 404

from wsgiref.simple_server import make_server

def routers():

    urlpatterns = (

        ('/book', f1),

        ('/web', f2),

    )

    return  urlpatterns

def f1(x):

    return [b'<h1>Hello, book</h1>']

def f2(x):

    return [b'<h1>Hello, web</h1>']

def application(environ, start_response):

    start_response('200 OK', [('Content-Type', 'text/html')])

    urlpatterns = routers()

    path = environ["PATH_INFO"]

    func = None

    for item in urlpatterns:

        if item[0] == path:

            func = item[1]

            break

    if func:

        return func(environ)

    else:

        return ["<h1>404</h1>".encode("utf8")]

httpd = make_server('', 8888, application)

print('Serving HTTP on port 8888...')

httpd.serve_forever()