如何在Golang中将[] byte XML转换为JSON输出

有没有办法在Golang中将XML（[] byte）转换为JSON输出？

body[]byteUnmarshalxml

// POST 
func (u *UserResource) authenticateUser(request *restful.Request, response *restful.Response) {
    App := new(Api)
    App.url = "http://api.com/api"
    usr := new(User)
    err := request.ReadEntity(usr)
    if err != nil {
        response.AddHeader("Content-Type", "application/json")
        response.WriteErrorString(http.StatusInternalServerError, err.Error())
        return
    }

    buf := []byte("<app version=\"1.0\"><request>1111</request></app>")
    r, err := http.Post(App.url, "text/plain", bytes.NewBuffer(buf))
    if err != nil {
        response.AddHeader("Content-Type", "application/json")
        response.WriteErrorString(http.StatusInternalServerError, err.Error())
        return
    }
    defer r.Body.Close()
    body, err := ioutil.ReadAll(r.Body)
    response.AddHeader("Content-Type", "application/json")
    response.WriteHeader(http.StatusCreated)
//  err = xml.Unmarshal(body, &usr)
//  if err != nil {
//      fmt.Printf("error: %v", err)
//      return
//  }
    response.Write(body)
//  fmt.Print(&usr.userName)
}

我也在使用Go-restful软件包