使用Go语言创建WebSocket服务的实现示例

GET /chat HTTP/1.1
 Host: server.example.com
 Upgrade: websocket
 Connection: Upgrade
 Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==
 Sec-WebSocket-Protocol: chat, superchat
 Sec-WebSocket-Version: 13
 Origin: http://example.com

HTTP/1.1 101 Switching Protocols
 Upgrade: websocket
 Connection: Upgrade
 Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=
 Sec-WebSocket-Protocol: chat

// HTTP server with WebSocket endpoint
func Server() {
  http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
   ws, err := NewHandler(w, r)
   if err != nil {
     // handle error
   }
   if err = ws.Handshake(); err != nil {
    // handle error
   }
  …

// NewHandler initializes a new handler
func NewHandler(w http.ResponseWriter, req *http.Request) (*WS, error) {
  hj, ok := w.(http.Hijacker)
  if !ok {
   // handle error
  }     .....
}

// Handshake creates a handshake header
 func (ws *WS) Handshake() error {

  hash := func(key string) string {
   h := sha1.New()
   h.Write([]byte(key))
   h.Write([]byte("258EAFA5-E914-47DA-95CA-C5AB0DC85B11"))

  return base64.StdEncoding.EncodeToString(h.Sum(nil))
  }(ws.header.Get("Sec-WebSocket-Key"))
  .....
}

// Recv receives data and returns a Frame
 func (ws *WS) Recv() (frame Frame, _ error) {
  frame = Frame{}
  head, err := ws.read(2)
  if err != nil {
   // handle error
  }

// Send sends a Frame
 func (ws *WS) Send(fr Frame) error {
  // make a slice of bytes of length 2
  data := make([]byte, 2)

  // Save fragmentation & opcode information in the first byte
  data[0] = 0x80 | fr.Opcode
  if fr.IsFragment {
   data[0] &= 0x7F
  }
  .....

// Close sends a close frame and closes the TCP connection
func (ws *Ws) Close() error {
 f := Frame{}
 f.Opcode = 8
 f.Length = 2
 f.Payload = make([]byte, 2)
 binary.BigEndian.PutUint16(f.Payload, ws.status)
 if err := ws.Send(f); err != nil {
  return err
 }
 return ws.conn.Close()
}

// handler/ws/echo.go
package ws

import (
	"fmt"
	"github.com/gorilla/websocket"
	"net/http"
)

var upgrader = websocket.Upgrader{
	ReadBufferSize: 1024,
	WriteBufferSize: 1024,
}

func EchoMessage(w http.ResponseWriter, r *http.Request) {
	conn, _ := upgrader.Upgrade(w, r, nil) // 实际应用时记得做错误处理

	for {
		// 读取客户端的消息
		msgType, msg, err := conn.ReadMessage()
		if err != nil {
			return
		}

		// 把消息打印到标准输出
		fmt.Printf("%s sent: %s\n", conn.RemoteAddr(), string(msg))

		// 把消息写回客户端，完成回音
		if err = conn.WriteMessage(msgType, msg); err != nil {
			return
		}
	}
}

// handler/ws/echo_display.go
package ws

import "net/http"

func DisplayEcho(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, "views/websockets.html")
}

<form>
 <input id="input" type="text" />
 <button onclick="send()">Send</button>
 <pre id="output"></pre>
</form>
...
<script>
 var input = document.getElementById("input");
 var output = document.getElementById("output");
 var socket = new WebSocket("ws://localhost:8000/ws/echo");

 socket.onopen = function () {
  output.innerHTML += "Status: Connected\n";
 };

 socket.onmessage = function (e) {
  output.innerHTML += "Server: " + e.data + "\n";
 };

 function send() {
  socket.send(input.value);
  input.value = "";
 }
</script>
...

// router/router.go
func RegisterRoutes(r *mux.Router) {
 ...
 wsRouter := r.PathPrefix("/ws").Subrouter()
 wsRouter.HandleFunc("/echo", ws.EchoMessage)
 wsRouter.HandleFunc("/echo_display", ws.DisplayEcho)
}