问tornado-MainHandler(RequestHandler) get参数api值是空？

tornado-MainHandler(RequestHandler) 中get参数api值一直是空

源码：

import json

import tornado.ioloop

import tornado.web

from tornado.web import RequestHandler , Application

class MainHandler(RequestHandler):

def get(self , api=""):

"""

根据用户请求的api，返回对应的数据

:param api : 用户请求的应用接口

"""

print("api is " , api)

if not api:

links = ["random" , "names" , "proxies" , "all" , "count"]

self.write("<h4>welcome to adsl api!</h4>")

for link in links:

self.write("<a href={link}> {link}</a><br/>".format(link=link))

def server(port=8000 , address=""):

"""

创建启动web服务器框架

"""

app = Application([

(r"/" , MainHandler) ,

(r"/.*" , MainHandler)

])

app.listen(port=port , address=address)

print("adsl api listen on " , port)

tornado.ioloop.IOLoop.instance().start()

if __name__ == "__main__":

server()