$Id: 212
$Score: 0
$SOId: 2704
[HandleFunc](<https://golang.org/pkg/net/http/#ListenAndServe>)
registers the handler function for the given pattern in the server mux (router).
You can pass define an anonymous function, as we have seen in the basic Hello World example:
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "Hello, world!")
}
But we can also pass a [HandlerFunc](<https://golang.org/pkg/net/http/#HandlerFunc>)
type. In other words, we can pass any function that respects the following signature:
func FunctionName(w http.ResponseWriter, req *http.Request)
We can rewrite the previous example passing the reference to a previously defined HandlerFunc
. Here’s the full example:
package main
import (
"fmt"
"net/http"
)
// A HandlerFunc function
// Notice the signature of the function
func RootHandler(w http.ResponseWriter, req *http.Request) {
fmt.Fprintln(w, "Hello, world!")
}
func main() {
// Here we pass the reference to the `RootHandler` handler function
http.HandleFunc("/", RootHandler)
panic(http.ListenAndServe(":8080", nil))
}
Of course, you can define several function handlers for different paths.
package main
import (
"fmt"
"log"
"net/http"
)
func FooHandler(w http.ResponseWriter, req *http.Request) {
fmt.Fprintln(w, "Hello from foo!")
}
func BarHandler(w http.ResponseWriter, req *http.Request) {
fmt.Fprintln(w, "Hello from bar!")
}
func main() {
http.HandleFunc("/foo", FooHandler)
http.HandleFunc("/bar", BarHandler)
log.Fatal(http.ListenAndServe(":8080", nil))
}
Here’s the output using cURL
:
$ curl -i localhost:8080/foo
HTTP/1.1 200 OK
Date: Wed, 20 Jul 2016 18:23:08 GMT
Content-Length: 16
Content-Type: text/plain; charset=utf-8
Hello from foo!
$ curl -i localhost:8080/bar
HTTP/1.1 200 OK
Date: Wed, 20 Jul 2016 18:23:10 GMT
Content-Length: 16
Content-Type: text/plain; charset=utf-8
Hello from bar!
$ curl -i localhost:8080/
HTTP/1.1 404 Not Found
Content-Type: text/plain; charset=utf-8
X-Content-Type-Options: nosniff
Date: Wed, 20 Jul 2016 18:23:13 GMT
Content-Length: 19
404 page not found