在 Gin 项目中使用 WebSocket

前言

实践是检验真理的唯一标准

正文

如何将Gin框架的后端与WebSocket服务写在一起, 以达到共用一个端口的情况呢?

我们来看单纯使用 net 包和 WS 结合

package main

import (
	"flag"
	"fmt"
	"log"
	"net/http"

	"github.com/gorilla/websocket"
)

var addr = flag.String("addr", "localhost:8080", "http service address")

var upgrader = websocket.Upgrader{
	// 解决跨域问题
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
} // use default options

func ws(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 main() {
	flag.Parse()
	log.SetFlags(0)
	http.HandleFunc("/ws", ws)
	fmt.Println(*addr)
	log.Fatal(http.ListenAndServe(*addr, nil))
}

其实本质来说, WS服务在握手的过程中最开始也是HTTP请求, 然后再 Upgrade 到WS模式的, Upgrade函数接受三个参数, 一个是返回值套接字, 一个是请求套接字, 一个是返回值的头, 而对于 Gin 的上下文 gin.Context 来说也是有这些数据的, 因此我们修改成

package control

import (
	"log"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{
	// 解决跨域问题
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
} // use default options

func cmdWebSocket(c *gin.Context) {
	ws, err := upgrader.Upgrade(c.Writer, c.Request, nil)
	if err != nil {
		log.Print("upgrade:", err)
		return
	}
	defer ws.Close()
	for {
		mt, message, err := ws.ReadMessage()
		if err != nil {
			log.Println("read:", err)
			break
		}
		log.Printf("recv: %s", message)
		err = ws.WriteMessage(mt, message)
		if err != nil {
			log.Println("write:", err)
			break
		}
	}
}

即可