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)

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/