我很难在Google Cloud Platform中显示指示请求的结果。这是我尝试过的：

package main

import (
    "fmt"
    "net/http"
    "context"
    "io/ioutil"
    "google.golang.org/appengine"
    "google.golang.org/appengine/urlfetch"
)

const directionAPIKey = "MyAppKey"
const directionURL = "https://maps.googleapis.com/maps/api/directions/json?origin=%s&destination=%s&mode=%s&key=%s"

func main() {
    http.HandleFunc("/",handler)
}

func handler(w http.ResponseWriter,r *http.Request) {
    ctx := appengine.NewContext(r)
    direction,err := fetchDirection(ctx,r.FormValue("origin"),r.FormValue("destination"),r.FormValue("mode"))
    if err != nil {
        http.Error(w,err.Error(),http.StatusInternalServerError)
        return
    }
    w.Header().Add("Content-Type","application/json; charset=utf-8")
    w.Write(direction)
}

func fetchDirection(ctx context.Context,origin string,destination string,mode string) ([]byte,error) {
    client := urlfetch.Client(ctx)
    resp,err := client.Get(fmt.Sprintf(directionURL,origin,destination,mode,directionAPIKey))
    if err != nil {
        return nil,err
    }
    defer resp.Body.Close()
    return ioutil.ReadAll(resp.Body)
}

我已经成功部署了我的应用程序，但是，以上代码的结果是：

Get https://maps.googleapis.com/maps/api/directions/json?origin=&destination=&mode=&key=APIKey not an App Engine context

而不是请求的结果。这是来自浏览器的 image 。如何获得理想的结果，而不仅仅是该URL？预先感谢。