Cara menggunakan Websocket golang untuk membangunkan fungsi peta masa nyata

package main import ( "log" "net/http" "github.com/gorilla/websocket" ) func main() { http.HandleFunc("/", serveHome) http.HandleFunc("/ws", handleWebSocket) if err := http.ListenAndServe(":8080", nil); err != nil { log.Fatal("ListenAndServe: ", err) } } func serveHome(w http.ResponseWriter, r *http.Request) { http.ServeFile(w, r, "index.html") } var upgrader = websocket.Upgrader{ ReadBufferSize: 1024, WriteBufferSize: 1024, } func handleWebSocket(w http.ResponseWriter, r *http.Request) { conn, err := upgrader.Upgrade(w, r, nil) if err != nil { log.Println(err) return } defer conn.Close() for { messageType, p, err := conn.ReadMessage() if err != nil { log.Println(err) return } log.Printf("Received message: %s", p) err = conn.WriteMessage(messageType, p) if err != nil { log.Println(err) return } } }

var socket = new WebSocket("ws://localhost:8080/ws"); socket.onopen = function(event) { socket.send("Hello, server!"); }; socket.onmessage = function(event) { console.log("Received message: " + event.data); };

package main import ( "encoding/json" "flag" "fmt" "html/template" "log" "net/http" "sync" "github.com/gorilla/websocket" ) const ( MapWidth = 800 MapHeight = 600 ) var ( port = flag.Int("port", 8888, "http listen port") addr = flag.String("addr", "localhost", "http server address") mu sync.Mutex connections map[*websocket.Conn]bool ) func init() { connections = make(map[*websocket.Conn]bool) } type Position struct { X float64 `json:"x"` Y float64 `json:"y"` } type Location struct { Name string `json:"name"` Position Position `json:"position"` } type Map struct { Name string `json:"name"` ImageURL string `json:"image_url"` Locations []Location `json:"locations"` } var ( maps = []Map{ Map{ Name: "Campus Map", ImageURL: "/static/campus_map.png", Locations: []Location{ Location{ Name: "Library", Position: Position{ X: 400, Y: 300, }, }, Location{ Name: "Dormitory Building", Position: Position{ X: 300, Y: 200, }, }, Location{ Name: "Teaching Building", Position: Position{ X: 500, Y: 400, }, }, }, }, } ) func main() { flag.Parse() http.HandleFunc("/", indexPageHandler) http.HandleFunc("/ws", wsHandler) staticHandler := http.FileServer(http.Dir("static")) http.Handle("/static/", http.StripPrefix("/static/", staticHandler)) addr := fmt.Sprintf("%s:%d", *addr, *port) log.Printf("Starting server on %s", addr) err := http.ListenAndServe(addr, nil) if err != nil { log.Fatal("ListenAndServe: ", err) } } func indexPageHandler(w http.ResponseWriter, r *http.Request) { indexTemplate := template.Must(template.ParseFiles("templates/index.html")) indexTemplate.ExecuteTemplate(w, "index.html", maps) } type Message struct { Action string `json:"action"` Location string `json:"location"` } func wsHandler(w http.ResponseWriter, r *http.Request) { ws, err := websocket.Upgrade(w, r, nil, 1024, 1024) if err != nil { http.Error(w, "Could not open websocket connection", http.StatusBadRequest) return } defer ws.Close() mu.Lock() connections[ws] = true mu.Unlock() for { msgType, msg, err := ws.ReadMessage() if err != nil { delete(connections, ws) return } else { log.Printf("Received: %s ", msg) m := &Message{} if err := json.Unmarshal(msg, m); err != nil { log.Printf("Failed to unmarshal message %s: %v", msg, err) } else { switch m.Action { case "move": sendUpdate(ws, m.Location) updateMap(m.Location) case "logout": delete(connections, ws) } } } for c := range connections { err = c.WriteMessage(msgType, msg) if err != nil { delete(connections, c) log.Printf("Error writing to user [%s]: %v ", c.RemoteAddr(), err) } } } } func updateMap(loc string) { for i := range maps { for j := range maps[i].Locations { if maps[i].Locations[j].Name == loc { maps[i].Locations[j].Position.X += 20 maps[i].Locations[j].Position.Y += 20 } } } } func sendUpdate(ws *websocket.Conn, loc string) { for i := range maps { if maps[i].Name == "Campus Map" { msg := &Message{ Action: "update", Location: loc, } for j := range maps[i].Locations { location := maps[i].Locations[j] msgBody, _ := json.Marshal(location) if err := ws.WriteMessage(websocket.TextMessage, msgBody); err != nil { log.Printf("Could not send message: %v", err) } } break } } }