限制在ASP.NET每个用户只有一个会话 [英] Limit only one session per user in ASP.NET

问题描述

反正是有检测，当用户登录，如果已经有另一个会话使用相同的用户名，并再次登录阻止他或给他发邮件？

Is there anyway to detect when a user logins if there is already another session with the same username, and block him from logging in again or send him a message?

推荐答案

您可以始终贯彻在Global.asax中的事件。

You could always implement the events in global.asax.

实施的Application_Start（）设置一个System.Collections.Dictionary（或你的preference），并存储在应用程序的[]集合，当用户logsin，添加用户名。从集合中删除Session_End中（）。请记住，使用了锁的关键字，而与收集工作：）

Implement Application_Start() to setup a System.Collections.Dictionary (or at your preference) and store that in the Application[] collection, when a user logsin, add the username. Remove from the collection in Session_End(). Remember to use the 'lock' keyword while working with the collection :)

玩得开心！

例如：

[page.aspx]
public partial class page : System.Web.UI.Page {
    protected bool Login(string userName) {
        System.Collections.Generic.List<string> d = Application["UsersLoggedIn"]
            as System.Collections.Generic.List<string>;
        if (d != null) {
            lock (d) {
                if (d.Contains(userName)) {
                    // User is already logged in!!!
                    return false;
                }
                d.Add(userName);
            }
        }
        Session["UserLoggedIn"] = userName;
        return true;
    }

    protected void Logout() {
        Session.Abandon();
    }
}

[global.asax]
<%@ Application Language="C#" %>
<script RunAt="server">
    void Application_Start(object sender, EventArgs e) {
        Application["UsersLoggedIn"] = new System.Collections.Generic.List<string>();
    }

    void Session_End(object sender, EventArgs e) {
        // NOTE: you might want to call this from the .Logout() method - aswell -, to speed things up
        string userLoggedIn = Session["UserLoggedIn"] == null ? string.Empty ? (string)Session["UserLoggedIn"];
        if (userLoggedIn.Length > 0) {
            System.Collections.Generic.List<string> d = Application["UsersLoggedIn"] 
                as System.Collections.Generic.List<string>;
            if (d != null) {
                lock (d) {
                    d.Remove(userLoggedIn);
                }
            }
        }
    }
</script>   

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