如何用Go语言开发一个简单的即时通讯应用

go mod init im_app

package main

import (
    "GitHub.com/gin-gonic/gin"
)

func main() {
    r := gin.Default()

    r.GET("/", func(c *gin.Context) {
        c.JSON(200, gin.H{
            "message": "Hello, World!",
        })
    })

    r.Run(":8000")
}

type User struct {
    Username string `json:"username"`
    PassWord string `json:"password"`
}

var users []User

func reGISter(c *gin.Context) {
    var user User
    err := c.ShouldBindJSON(&user)
    if err != nil {
        c.JSON(400, gin.H{"error": "Invalid request payload"})
        return
    }

    users = append(users, user)
    c.JSON(200, gin.H{"message": "Registration successful"})
}

func login(c *gin.Context) {
    var user User
    err := c.ShouldBindJSON(&user)
    if err != nil {
        c.JSON(400, gin.H{"error": "Invalid request payload"})
        return
    }

    for _, u := range users {
        if u.Username == user.Username && u.Password == user.Password {
            c.JSON(200, gin.H{"message": "Login successful"})
            return
        }
    }

    c.JSON(401, gin.H{"error": "Invalid username or password"})
}

import (
    "github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{
    ReadBufferSize:  1024,
    WriteBufferSize: 1024,
    CheckOrigin: func(r *http.Request) bool {
        return true
    },
}

func wsHandler(c *gin.Context) {
    conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
    if err != nil {
        log.Println("Failed to upgrade:", err)
        return
    }
    defer conn.Close()

    for {
        _, msg, err := conn.ReadMessage()
        if err != nil {
            log.Println("Failed to read message:", err)
            break
        }
        log.Printf("Received: %s", msg)

        err = conn.WriteMessage(websocket.TextMessage, []byte("Received: "+string(msg)))
        if err != nil {
            log.Println("Failed to write message:", err)
            break
        }
    }
}

import (
    "github.com/go-redis/redis"
)

var redisClient *redis.Client

func init() {
    redisClient = redis.NewClient(&redis.Options{
        Addr:     "localhost:6379",
        Password: "", // 如果没有设置密码的话，这里留空
        DB:       0,
    })

    pong, err := redisClient.Ping().Result()
    if err != nil {
        log.Fatal("Failed to connect to Redis:", err)
    }
    log.Println("Connected to Redis:", pong)
}

func onlineStatus(c *gin.Context) {
    username := c.Query("username")
    if username == "" {
        c.JSON(400, gin.H{"error": "Invalid username"})
        return
    }

    err := redisClient.Set(username, "online", 0).Err()
    if err != nil {
        log.Println("Failed to set online status:", err)
        c.JSON(500, gin.H{"error": "Internal server error"})
        return
    }

    c.JSON(200, gin.H{"message": "Online status updated"})
}

go run main.go