golang gorilla websocket例子

WebSocket协议是基于TCP的一种新的网络协议。它实现了浏览器与服务器全双工(full-duplex)通信——允许服务器主动发送信息给客户端。
WebSocket通信协议于2011年被IETF定为标准RFC 6455，并被RFC7936所补充规范。

在golang语言中，目前有两种比较常用的实现方式：一个是golang自带的库，另一个是gorilla，功能强大。

golang自带库的使用例子可参考以前的博文:Golang如何使用websocket

本文以gorilla为例，介绍websocket的使用。

下载gorilla

# go get github.com/gorilla/websocket

下面例子中主要包括两部分，server和client。
client部分又包括：web client(浏览器)和非web client。

server

server端是一个HTTP 服务器，监听8080端口。

当接收到连接请求后，将连接使用的http协议升级为websocket协议。后续通信过程中，使用websocket进行通信。

对每个连接，server端等待读取数据，读到数据后，打印数据，然后，将数据又发送给client.

server启动方式

# go run server.go

server.go代码如下：

// Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ignore

package main

import (
    "flag"
    "html/template" "log" "net/http" "github.com/gorilla/websocket" ) var addr = flag.String("addr", "localhost:8080", "http service address") var upgrader = websocket.Upgrader{} // use default options func echo(w http.ResponseWriter, r *http.Request) { c, err := upgrader.Upgrade(w, r, nil) if err != nil { log.Print("upgrade:", err) return } defer c.Close() for { mt, message, err := c.ReadMessage() if err != nil { log.Println("read:", err) break } log.Printf("recv: %s", message) err = c.WriteMessage(mt, message) if err != nil { log.Println("write:", err) break } } } func home(w http.ResponseWriter, r *http.Request) { homeTemplate.Execute(w, "ws://"+r.Host+"/echo") } func main() { flag.Parse() log.SetFlags(0) http.HandleFunc("/echo", echo) http.HandleFunc("/", home) log.Fatal(http.ListenAndServe(*addr, nil)) } var homeTemplate = template.Must(template.New("").Parse(` <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <script> window.addEventListener("load", function(evt) { var output = document.getElementById("output"); var input = document.getElementById("input"); var ws; var print = function(message) { var d = document.createElement("div"); d.innerHTML = message; output.appendChild(d); }; document.getElementById("open").onclick = function(evt) { if (ws) { return false; } ws = new WebSocket("{{.}}"); ws.onopen = function(evt) { print("OPEN"); } ws.onclose = function(evt) { print("CLOSE"); ws = null; } ws.onmessage = function(evt) { print("RESPONSE: " + evt.data); } ws.onerror = function(evt) { print("ERROR: " + evt.data); } return false; }; document.getElementById("send").onclick = function(evt) { if (!ws) { return false; } print("SEND: " + input.value); ws.send(input.value); return false; }; document.getElementById("close").onclick = function(evt) { if (!ws) { return false; } ws.close(); return false; }; }); </script> </head> <body> <table> <tr><td valign="top" width="50%"> <p>Click "Open" to create a connection to the server, "Send" to send a message to the server and "Close" to close the connection. You can change the message and send multiple times. <p> <form> <button id="open">Open</button> <button id="close">Close</button> <p><input id="input" type="text" value="Hello world!"> <button id="send">Send</button> </form> </td><td valign="top" width="50%"> <div id="output"></div> </td></tr></table> </body> </html> `))

server output:

recv: 2018-10-20 17:09:12.497129965 +0800 CST m=+1.010137585
recv: 2018-10-20 17:09:13.495602484 +0800 CST m=+2.008641088
recv: 2018-10-20 17:09:14.49401062 +0800 CST m=+3.007080206
recv: 2018-10-20 17:09:15.497114615 +0800 CST m=+4.010215329
recv: 2018-10-20 17:09:16.494394706 +0800 CST m=+5.007526368
read: websocket: close 1000 (normal)

非web client

client启动后，首先连接server。

连接建立后，主routine每一秒钟向server发送消息(当前时间)。

另一个routine从server接收数据,并打印。

当client退出时，会向server发送关闭消息。接着，等待退出。

client启动方式

# go run client.go

client代码如下:

// Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ignore

package main import ( "flag" "log" "net/url" "os" "os/signal" "time" "github.com/gorilla/websocket" ) var addr = flag.String("addr", "localhost:8080", "http service address") func main() { flag.Parse() log.SetFlags(0) interrupt := make(chan os.Signal, 1) signal.Notify(interrupt, os.Interrupt) u := url.URL{Scheme: "ws", Host: *addr, Path: "/echo"} log.Printf("connecting to %s", u.String()) c, _, err := websocket.DefaultDialer.Dial(u.String(), nil) if err != nil { log.Fatal("dial:", err) } defer c.Close() done := make(chan struct{}) go func() { defer close(done) for { _, message, err := c.ReadMessage() if err != nil { log.Println("read:", err) return } log.Printf("recv: %s", message) } }() ticker := time.NewTicker(time.Second) defer ticker.Stop() for { select { case <-done: return case t := <-ticker.C: err := c.WriteMessage(websocket.TextMessage, []byte(t.String())) if err != nil { log.Println("write:", err) return } case <-interrupt: log.Println("interrupt") // Cleanly close the connection by sending a close message and then // waiting (with timeout) for the server to close the connection. err := c.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")) if err != nil { log.Println("write close:", err) return } select { case <-done: case <-time.After(time.Second): } return } } }

client output:

connecting to ws://localhost:8080/echo
recv: 2018-10-20 17:09:12.497129965 +0800 CST m=+1.010137585
recv: 2018-10-20 17:09:13.495602484 +0800 CST m=+2.008641088
recv: 2018-10-20 17:09:14.49401062 +0800 CST m=+3.007080206
recv: 2018-10-20 17:09:15.497114615 +0800 CST m=+4.010215329
recv: 2018-10-20 17:09:16.494394706 +0800 CST m=+5.007526368
^Cinterrupt
read: websocket: close 1000 (normal)