golang 怎么修改路由

go get -u GitHub.com/gorilla/mux

package main
  
import (
    "encoding/JSON"
    "log"
    "net/http"
 
    "github.com/gorilla/mux"
)
 
type Product struct {
    ID    string  `json:"id"`
    Name  string  `json:"name"`
    Price float64 `json:"price"`
}
  
var products []Product
  
func getProducts(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(products)
}
  
func getProduct(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    params := mux.Vars(r)
    for _, item := range products {
        if item.ID == params["id"] {
            json.NewEncoder(w).Encode(item)
            return
        }
    }
    json.NewEncoder(w).Encode(&Product{})
}
  
func main() {
    router := mux.NewRouter()
 
    products = append(products, Product{ID: "1", Name: "Product 1", Price: 29.99})
    products = append(products, Product{ID: "2", Name: "Product 2", Price: 39.99})
    products = append(products, Product{ID: "3", Name: "Product 3", Price: 49.99})
 
    router.HandleFunc("/products", getProducts).Methods("GET")
    router.HandleFunc("/products/{id}", getProduct).Methods("GET")
 
    log.Fatal(http.ListenAndServe(":8000", router))
}