仅带有标准库的Golang中间件

Question

My first stackoverflow question, so please go easy on my naivety about stackoverflow and the question asked, beginner in golang.

I would like to know the difference between the two calls and also simple understanding of the Handle, Handler, HandleFunc, HandlerFunc.

http.Handle("/profile", Logger(profilefunc))
http.HandleFunc("/", HomeFunc)

func main() {            
   fmt.Println("Starting the server.")

   profilefunc := http.HandlerFunc(ProfileFunc)

   http.Handle("/profile", Logger(profilefunc))
   http.HandleFunc("/", HomeFunc)

   http.ListenAndServe("0.0.0.0:8081", nil)
}

func Logger(h http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request){
        log.Println("Before serving request")
        h.ServeHTTP(w, r)
        log.Println("After serving request")
    })
}

func ProfileFunc(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "You are on the profile page.")
}

func HomeFunc(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello Imran Pochi")
}

Answer 1

I would like ... simple understanding of the Handle, Handler, HandleFunc, HandlerFunc.

• Handler is an interface that can respond to an HTTP request and has a ServeHTTP(ResponseWriter, *Request) method.
• http.Handle registers a Handler to handle HTTP requests matching a given pattern.
• http.HandleFunc registers a handler function to handle HTTP requests matching a given pattern. The handler function should be of the form func(ResponseWriter, *Request).
• HandlerFunc is an explicit function type of the form func(ResponseWriter, *Request). HandlerFunc has a method ServeHTTP that calls itself . This allows you to cast a function to a HandlerFunc and use it as a Handler.

I would to know the difference between the two calls

http.Handle("/profile", Logger(profilefunc))
http.HandleFunc("/", HomeFunc)

Logger is an example of a middleware, which is a function that takes an http.Handler and it returns another http.Handler that wraps the original handler. When called this handler may (or may not) call the nested http.Handler before and/or after performing some operation. So the first line is saying register the profileFunc Handler wrapped in the Logger middleware with the pattern "/profile". The second line is saying register the HomeFunc function with the "/" pattern.