bugfix: can not get schema from http.Request.URL
bugfix: can not get schema from http.Request.URL

can not get request schema from http.Request.URL，because

[Request doc](https://golang.org/pkg/net/http/#Request)

        // For server requests the URL is parsed from the URI
        // supplied on the Request-Line as stored in RequestURI.  For
        // most requests, fields other than Path and RawQuery will be
        // empty. (See RFC 2616, Section 5.1.2)
        URL *url.URL
yookoala/gofast,yookoala/gofast,yookoala/gofast,yookoala/gofast