tornado 里面如何使用Future中的数据？

Question

tonado官方文档（http://www.tornadoweb.org/en/stable/gen.html）
可以通过定义以下方法获取异步返回值：
@gen.coroutine
def fetch_json(url):
response = yield AsyncHTTPClient().fetch(url)
raise gen.Return(json_decode(response.body))

但是以下代码调用fetch_json方法，得到一个数据（tornado.concurrent.Future），在get方法里面怎么获取返回的response.body的值？

class TestHandler(BaseHtHandler):
@asynchronous
def get(self):
log.info("TestHandler.get")
self.set_header("Access-Control-Allow-Origin", "*")
response=self.fetch_json("http://www.baidu.com")
self.finish()

Answer 1

from tornado.web import RequestHandler, Application, asynchronous
from tornado.ioloop import IOLoop
from tornado.httpserver import HTTPServer
from tornado import gen
from tornado.httpclient import AsyncHTTPClient

class IndexHandler(RequestHandler):
    @asynchronous
    @gen.coroutine
    def get(self):
        response = self.fetch_json('http://www.qq.com')
        result = yield response
        self.write(result)
        self.finish()

    @gen.coroutine
    def fetch_json(self, url):
        response = yield AsyncHTTPClient().fetch(url)
        raise gen.Return(response.body)

app = Application([('/', IndexHandler)], debug = True)
http_server = HTTPServer(app)
http_server.listen(1888)
IOLoop.instance().start()