Golang: HTTP Server

Jul 26, 2022

—

// Signature
func HandleFunc(pattern string, handler func(ResponseWriter, *Request))

Go
​x
 
// Signature
func HandleFunc(pattern string, handler func(ResponseWriter, *Request))

func main() {

	http.HandleFunc("/ping", func(w http.ResponseWriter, r *http.Request) {

		// Method #1
		w.Write([]byte("hello from w.Write"))
		// Method #2
		io.WriteString(w, "hello from io.WriteString")
		// Method #3
		fmt.Fprintf(w, "hello from fmt.Fprintf")
	})

	http.ListenAndServe(":8080", nil)
}

Go
 
func main() {
​
    http.HandleFunc("/ping", func(w http.ResponseWriter, r *http.Request) {
​
        // Method #1
        w.Write([]byte("hello from w.Write"))
        // Method #2
        io.WriteString(w, "hello from io.WriteString")
        // Method #3
        fmt.Fprintf(w, "hello from fmt.Fprintf")
    })
​
    http.ListenAndServe(":8080", nil)
}

To test, you can run:

curl localhost:8080/ping

Shell
 
curl localhost:8080/ping

It should response one of the three methods (or all three).

UPDATE:

Before Golang version 1.22, you only can define “path” as the first argument of http.HandleFunc.

But, starting from Golang version 1.22 the pattern becomes:

[METHOD ][HOST]/[PATH]

 
[METHOD ][HOST]/[PATH]

Please check here for more information about the new pattern https://pkg.go.dev/net/http#hdr-Patterns.

References:

Golang: HTTP Server

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