如何在不使用DefaultServeMux的情况下实现HandlerFunc

Question

如果我要使用DefaultServeMux（我将其指定nil为ListenAndServe的第二个参数来指定），那么我可以访问http.HandleFunc，您可以在Go
Wiki的以下示例中看到该：

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

在当前代码中，我无法使用DefaultServeMux，即我将自定义处理程序传递给ListenAndServe

    h := &mypackage.Handler{
        Database: mydb
    }
    http.ListenAndServe(":8080", h)

因此，我没有http.HandleFunc内置的代码。但是，我必须将一些授权代码修改为需要类似的授权代码http.HandleFunc。例如，如果我一直在使用DefaultServeMux，则当我点击"/protected"路线时，我想转到Protected处理程序，但仅在经过h.AuthorizationHandlerFunc这样的处理之后

   h.AuthorizationHandlerFunc(Protected)

但是，由于我没有使用DefaultServeMux，因此无法正常工作，即无法将Protected函数（并调用它）传递给AuthorizationHandlerFunc。这是下面的AuthorizationHandlerFunc的实现。您可以在下面看到Protected永不被调用。

问题：HandlerFunc在这种情况下（不使用DefaultServeMux）如何实现？

func (h *Handler) AuthorizationHandlerFunc(next http.HandlerFunc) http.Handler{
     return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request){
         h.AuthorizationMiddleWare(w, r, next)
   })
}

func (h *Handler) AuthorizationMiddleWare(w http.ResponseWriter, r *http.Request, next http.HandlerFunc){
     //other stuff happens
     log.Println("this is never getting called")
     next(w,r)
}
func (h *Handler)Protected(w http.ResponseWriter, r *http.Request){

      log.Println("this is never getting called")
}

更新
ServeHTTP在mypackage.Handler上实现。为什么未调用Protected函数，或者为什么没有在AuthorizationMiddleWare中调用相关代码？

Answer 1

将您的授权中间件重新实现为http.Handler：

type auth struct {
   DB *sql.DB
   UnauthorizedHandler http.Handler
}

func NewAuth(db *sql.DB, unauthorized http.Handler) *auth {
    return auth{db, unauthorized}
}

func (a *auth) Protected(h http.Handler) http.Handler {
    fn := func(w http.ResponseWriter, r *http.Request) {
        // Check whether the request is valid
        // If it's invalid, call your error func and make sure to *return* early!
        if !valid {
            a.UnauthorizedHandler.ServeHTTP(w, r)
            return
        }
        // Call the next handler on success
        h.ServeHTTP(w, r)
        return
    }

    return http.HandlerFunc(fn)
}

func someHandler(w http.ResponseWriter, r *http.Request) {
    io.WriteString(w, "Hello!\n")
}

func main() {
    auth := NewAuth(db, errorHandler)
    r := http.NewServeMux()
    // We have a http.Handler implementation that wraps a http.HandlerFunc
    // ... so we call r.Handle on our ServeMux and type-cast the wrapped func
    r.Handle("/protected", auth.Protected(http.HandlerFunc(someHandler)))
    // Just a simple http.HandlerFunc here
    r.HandleFunc("/public", someOtherHandler)

    log.Fatal(http.ListenAndServe(":8000", r))
}

Take a look at the httpauth lib I
wrote
for a
different example with a ServeHTTP method. Both the above and explicitly
creating a ServeHTTP method on your type are valid approaches.