Golang 错误：未定义：http.NewSingleHostReverseProxy

Question

我尝试使用 Golang 构建一个简单的程序，这里是：

package main

import (

        "net/http"

        "net/http/httputil"

        "log"

)

func main(){

        proxy := http.NewSingleHostReverseProxy( &http.URL{Scheme:"http",Host:"www.google.com",Path:"/"})

        err := http.ListenAndServe(":8080", proxy)

        if err != nil {

                log.Fatal("ListenAndServe: ", err.String())

        }

}

建造：

go build myprogram.go

输出：

command-line-arguments

./myprogram.go:5: imported and not used: "net/http/httputil"

./myprogram.go:11: undefined: http.NewSingleHostReverseProxy

./myprogram.go:11: undefined: http.URL

./myprogram.go:15: err.String undefined (type error has no field or method String)

我注意到 http.NewSingleHostReverseProxy 在“net/http/httputil”包中，为什么我会看到这样的错误？也许我需要一个特定的命令来正确构建它？

编辑 后记，这是新的工作代码：

package main

import (

        "net/http"

        "net/http/httputil"

        "net/url"

        "log"

)

func main(){

        proxy := httputil.NewSingleHostReverseProxy( &url.URL{Scheme:"http",Host:"www.google.com",Path:"/"})

        err := http.ListenAndServe(":8080", proxy)

        if err != nil {

                log.Fatal("ListenAndServe: ", err)

        }

}