Go by Example: HTTP Servers

Writing a basic HTTP server is easy using the `net/http` package.	package main
	import ( "fmt" "net/http" )
A fundamental concept in `net/http` servers is handlers. A handler is an object implementing the `http.Handler` interface. A common way to write a handler is by using the `http.HandlerFunc` adapter on functions with the appropriate signature.	func hello(w http.ResponseWriter, req *http.Request) {
Functions serving as handlers take a `http.ResponseWriter` and a `http.Request` as arguments. The response writer is used to fill in the HTTP response. Here our simple response is just “hello\n”.	fmt.Fprintf(w, "hello\n") }
	func headers(w http.ResponseWriter, req *http.Request) {
This handler does something a little more sophisticated by reading all the HTTP request headers and echoing them into the response body.	for name, headers := range req.Header { for _, h := range headers { fmt.Fprintf(w, "%v: %v\n", name, h) } } }
	func main() {
We register our handlers on server routes using the `http.HandleFunc` convenience function. It sets up the default router in the `net/http` package and takes a function as an argument.	http.HandleFunc("/hello", hello) http.HandleFunc("/headers", headers)
Finally, we call the `ListenAndServe` with the port and a handler. `nil` tells it to use the default router we’ve just set up.	http.ListenAndServe(":8090", nil) }

Run the server in the background.	$ go run http-servers.go &
Access the `/hello` route.	$ curl localhost:8090/hello hello

Next example: Context.