im 框架 -- gorilla

项目地址：
https://github.com/gorilla/websocket

websocket 在线调试工具：
https://www.lddgo.net/network/websocket

示例代码：

1. 目录结构：

   |—— gorilla/   // 根目录
   ****|—— client/
   ********|—— main.go  // 客户端
   ****|—— server/
   ********|—— main.go  // 服务端

2. server/main.go：

    package main
   
    import (
        "context"
        "fmt"
        "github.com/gin-gonic/gin"
        "github.com/gorilla/websocket"
        "net/http"
        "os"
        "os/signal"
        "syscall"
        "time"
    )
   
    const (
        Address = "localhost:8091"
    )
   
    func checkToken(token string) bool {
        return true
    }
   
    func Chat(ctx *gin.Context) {
        token := ctx.GetHeader("token")
        // 校验 token 是否合法
        islegal := checkToken(token)
   
        conn, err := (&websocket.Upgrader{
            CheckOrigin: func(r *http.Request) bool {
                return islegal
            },
        }).Upgrade(ctx.Writer, ctx.Request, nil)
   
        if err != nil {
            fmt.Println("upgrade error:", err)
            return
        }
   
        // 发送消息
        go func() {
            for {
                err := conn.WriteMessage(websocket.TextMessage, []byte("hello from server!"))
                if err != nil {
                    fmt.Println(err.Error())
                    return
                }
                time.Sleep(3 * time.Second)
            }
        }()
        // 接收消息
        for {
            _, data, err := conn.ReadMessage()
            if err != nil {
                fmt.Println(err.Error())
                return
            }
            fmt.Println("message from client:", string(data))
        }
    }
   
    func main() {
        quit := make(chan os.Signal, 1) // 退出信号
        signal.Notify(quit, syscall.SIGKILL, syscall.SIGQUIT, syscall.SIGINT, syscall.SIGTERM)
        r := gin.Default()
        r.GET("/chat", Chat)
        srv := &http.Server{
            Addr:    Address,
            Handler: r,
        }
        go shutdown(quit, srv)
        fmt.Printf("server running at:%s \n", Address)
        if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
            panic(err)
        }
    }
   
    func shutdown(quit chan os.Signal, srv *http.Server) {
        <-quit
        ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
        defer cancel()
        fmt.Println("server shutdown...")
        if err := srv.Shutdown(ctx); err != nil {
            fmt.Println("shutdown error:", err)
        }
        os.Exit(0)
    }

3. 启动 server/main.go（略）

4. client/main.go：

    package main
   
    import (
        "fmt"
        "github.com/gorilla/websocket"
        "net/http"
        "os"
        "os/signal"
        "syscall"
        "time"
    )
   
    var msgChan = make(chan string)
   
    func wsClient() {
        quit := make(chan os.Signal, 1)
        signal.Notify(quit, syscall.SIGKILL, syscall.SIGQUIT, syscall.SIGINT, syscall.SIGTERM)
   
        token := ""
   
        socketUrl := "ws://localhost:8091" + "/chat"
        header := http.Header{}
        header.Add("token", token)
        conn, _, err := websocket.DefaultDialer.Dial(socketUrl, header)
        if err != nil {
            panic(err)
        }
        defer conn.Close()
   
        // 发送消息
        go func() {
            for {
                select {
                case msg := <-msgChan:
                    err := conn.WriteMessage(websocket.TextMessage, []byte(msg))
                    if err != nil {
                        fmt.Println("write error:", err)
                    }
                case <-quit:
                    fmt.Println("control + c pressed!")
                    err := conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
                    if err != nil {
                        fmt.Println("send close message error:", err)
                        os.Exit(0)
                    }
                    if err := conn.Close(); err != nil {
                        fmt.Println("conn close error:", err)
                        os.Exit(0)
                    }
                    os.Exit(0)
                }
            }
        }()
        // 接收消息
        for {
            _, msg, err := conn.ReadMessage()
            if err != nil {
                fmt.Println("Error in receive:", err)
                return
            }
            fmt.Println("message from server:", string(msg))
        }
    }
   
    func main() {
        go wsClient()
        // 将要发送到服务端的消息传递到消息管道
        for i := 0; i < 3; i++ {
            msgChan <- "hello from client!"
            time.Sleep(3 * time.Second)
        }
        select {}
    }

5. 启动 client/main.go（略）