我是 Go 新手，现在正在用它构建一个简单的 API：
package main
import (
"encoding/json"
"fmt"
"github.com/gorilla/mux"
"github.com/gorilla/handlers"
"log"
"net/http"
)
func main() {
port := ":3000"
var router = mux.NewRouter()
router.HandleFunc("/m/{msg}", handleMessage).Methods("GET")
router.HandleFunc("/n/{num}", handleNumber).Methods("GET")
headersOk := handlers.AllowedHeaders([]string{"Authorization"})
originsOk := handlers.AllowedOrigins([]string{"*"})
methodsOk := handlers.AllowedMethods([]string{"GET", "POST", "OPTIONS"})
fmt.Printf("Server is running at http://localhost%s\n", port)
log.Fatal(http.ListenAndServe(port, handlers.CORS(originsOk, headersOk, methodsOk)(router)))
}
func handleMessage(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
message := vars["msg"]
response := map[string]string{"message": message}
w.Header().Set("Content-Type", "application/json") // this
json.NewEncoder(w).Encode(response)
}
func handleNumber(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
number := vars["num"]
response := map[string]string{"number": number}
w.Header().Set("Content-Type", "application/json") // and this
json.NewEncoder(w).Encode(response)
}
感觉一直重复不干净w.Header().Set("Content-Type", "application/json")我拥有的每个 API 函数中都有一行。
所以我的问题是，是否可以为我拥有的所有 API 函数全局设置 http.ResponseWriter Content-Type 标头？
您可以定义middleware对于多路复用器路由器，这是一个示例：
func main() {
port := ":3000"
var router = mux.NewRouter()
router.Use(commonMiddleware)
router.HandleFunc("/m/{msg}", handleMessage).Methods("GET")
router.HandleFunc("/n/{num}", handleNumber).Methods("GET")
// rest of code goes here
}
func commonMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Content-Type", "application/json")
next.ServeHTTP(w, r)
})
}
阅读更多内容文档 http://www.gorillatoolkit.org/pkg/mux
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