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 ignorepackage mainimport ("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 optionsfunc 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 ignorepackage mainimport ("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:returncase 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)

web client

web client，也就是使用浏览器。
在浏览器中输入http://127.0.0.1:8080

“Open”，然后"send"

server output:

recv: Hello world!

参考

百度百科

https://baike.baidu.com/item/WebSocket

github

https://github.com/gorilla/websocket

doc

https://godoc.org/github.com/gorilla/websocket

example

https://github.com/gorilla/websocket/blob/master/examples/