Golang多用户登录实现方法详解

type User struct {
    ID       int
    Username string
    Password string // 存储哈希值
    Email    string
}

import "golang.org/x/crypto/bcrypt"

func hashPassword(password string) (string, error) {
    bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
    return string(bytes), err
}

func checkPassword(hash, password string) bool {
    err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
    return err == nil
}

func loginHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method == "GET" {
        // 返回登录页面
        tmpl.ExecuteTemplate(w, "login", nil)
        return
    }

    username := r.FormValue("username")
    password := r.FormValue("password")

    var user User
    // 查询数据库获取用户
    err := db.QueryRow("SELECT id, username, password FROM users WHERE username = ?", username).Scan(&user.ID, &user.Username, &user.Password)
    if err != nil || !checkPassword(user.Password, password) {
        http.Error(w, "用户名或密码错误", 401)
        return
    }

    // 登录成功，创建会话
    createSession(w, user.ID)
    http.Redirect(w, r, "/dashboard", 302)
}

var sessions = make(map[string]int) // sessionID -> userID
var sessionsMutex sync.Mutex

func createSession(w http.ResponseWriter, userID int) string {
    sessionID := generateSessionID() // 可用crypto/rand生成
    sessionsMutex.Lock()
    sessions[sessionID] = userID
    sessionsMutex.Unlock()

    http.SetCookie(w, &http.Cookie{
        Name:  "session_id",
        Value: sessionID,
        Path:  "/",
    })
    return sessionID
}

func authMiddleware(next http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        cookie, err := r.Cookie("session_id")
        if err != nil {
            http.Redirect(w, r, "/login", 302)
            return
        }

        sessionsMutex.Lock()
        userID, exists := sessions[cookie.Value]
        sessionsMutex.Unlock()

        if !exists {
            http.Redirect(w, r, "/login", 302)
            return
        }

        // 将用户ID传给后续处理函数
        ctx := context.WithValue(r.Context(), "userID", userID)
        next(w, r.WithContext(ctx))
    }
}