Hello world HTTP server example

A basic web server

If you access the URL http://localhost:8080/world on a machine where the program below is running, you will be greeted by this page.

package main

import (
    "fmt"
    "net/http"
)

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

func HelloServer(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, %s!", r.URL.Path[1:])
}

• The call to http.HandleFunc tells the net.http package to handle all requests to the web root with the HelloServer function.
• The call to http.ListenAndServe tells the server to listen on the TCP network address :8080. This function blocks until the program is terminated.
• Writing to an http.ResponseWriter sends data to the HTTP client.
• An http.Request is a data structure that represents a client HTTP request.
• r.URL.Path is the path component of the requested URL. In this case, "/world" is the path component of "http://localhost:8080/world".

Further reading: a complete wiki

The Writing Web Applications tutorial shows how to extend this small example into a complete wiki.

The tutorial covers how to

• create a data structure with load and save methods,
• use the net/http package to build web applications,
• use the html/template package to process HTML templates,
• use the regexp package to validate user input.

More code examples

Go blueprints: code for com­mon tasks is a collection of handy code examples.

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