How to Use net.Conn and net.Listener in Go

Use net.Listen to create a net.Listener that accepts incoming connections, then call Accept() to get a net.Conn for reading and writing data.

package main

import (
	"fmt"
	"io"
	"log"
	"net"
)

func main() {
	ln, err := net.Listen("tcp", ":8080")
	if err != nil {
		log.Fatal(err)
	}
	defer ln.Close()

	for {
		conn, err := ln.Accept()
		if err != nil {
			log.Println(err)
			continue
		}
		go handleConnection(conn)
	}
}

func handleConnection(conn net.Conn) {
	defer conn.Close()
	buf := make([]byte, 1024)
	n, err := conn.Read(buf)
	if err != nil && err != io.EOF {
		log.Println(err)
		return
	}
	fmt.Printf("Received: %s\n", string(buf[:n]))
	conn.Write([]byte("Hello from server"))
}

Think of net.Listener as a phone number waiting for calls and net.Conn as the actual phone call once someone dials in. You set up the listener to watch a specific port, and when a client connects, you get a connection object to send and receive messages. This is the standard way to build network servers in Go.