利用HttpModuler实现WEB程序同一时间只让一个用户

我在们使用ASP.Net开发WEB网站时，有的时候是不让同一个用户名在同一时间进行多次登陆的。
      为了不影响原来的整个网站，我选择使用了HttpModuler来实现。

      先让所有的Page从自己的Page类：BasePage类继承，并实现 ISigleLogin接口。相关代码如下：

public interface ISingleLogin{    string SigleUserLoginId { get; }    void SigleUserLogout();}public class BasePage : System.Web.UI.Page, BNet.Web.Modulers.ISingleLogin{    public BasePage()    {        //        // TODO: 在此处添加构造函数逻辑        //    }    protected override void OnLoad(EventArgs e)    {        base.OnLoad(e);        if (Session["UserId"] == null)        {            Response.Write("你还没有登陆");            Response.Redirect("login.aspx");        }    }    #region ISingleLogin 成员    public string SigleUserLoginId    {        get        {            if (Session["UserId"] != null)            {                return Session["UserId"].ToString();            }            else                return "";        }    }    public void SigleUserLogout()    {        Session.Abandon();        Response.Write("你在别处已经登陆，强制退出本次登陆!");    }    #endregion}

后在Web.config中加入HttpModuler：

 

<system.web>    <httpModules>      <add name="SingleLogin" type="BNet.Web.Modulers.SingleLoginModuler"/>    httpModules>system.web><system.web>
    <httpModules>
      <add name="SingleLogin" type="BNet.Web.Modulers.SingleLoginModuler"/>

 

    </httpModules>
</system.web>

相关的SigleLoginModuler代码如下：

 

using System;using System.Collections.Generic;using System.Data;using System.Configuration;using System.Web;using System.Web.UI;namespace BNet.Web.Modulers{    /// 
    /// SingleLoginModuler 的摘要说明    ///     public class SingleLoginModuler : System.Web.IHttpModule    {        const string sigle_login_userid = "evlon_siglelogin_userid";        const string sigle_pre_logout_sessionid = "evlon_sigle_pre_logout_sessionid";        static StringLifeValueDictionary loginedUserIdDictionary = null;        static StringLifeValueDictionary LoginedUserIdDictionary        {            get            {                if (loginedUserIdDictionary == null)                {                    loginedUserIdDictionary = new StringLifeValueDictionary();                }                else                {                    List<string> listRemove = new List<string>();                    StringLifeValueDictionary.Enumerator iter = 
                                         loginedUserIdDictionary.GetEnumerator();                    while (iter.MoveNext())                    {                        if (iter.Current.Value.life < DateTime.Now)                        {                            listRemove.Add(iter.Current.Key);                        }                    }                    foreach (string key in listRemove)                    {                        loginedUserIdDictionary.Remove(key);                    }                }                return loginedUserIdDictionary;            }        }        static StringLifeValueDictionary preLogoutSessionIdDictionary = null;        static StringLifeValueDictionary PreLogoutSessionIdDictionary        {            get            {                if (preLogoutSessionIdDictionary == null)                {                    preLogoutSessionIdDictionary = new StringLifeValueDictionary();                }                else                {                    List<string> listRemove = new List<string>();                    StringLifeValueDictionary.Enumerator iter =
                                       preLogoutSessionIdDictionary.GetEnumerator();                    while (iter.MoveNext())                    {                        if (iter.Current.Value.life < DateTime.Now)                        {                            listRemove.Add(iter.Current.Key);                        }                    }                    foreach (string key in listRemove)                    {                        preLogoutSessionIdDictionary.Remove(key);                    }                }                return preLogoutSessionIdDictionary;            }        }        public SingleLoginModuler()        {            //            // TODO: 在此处添加构造函数逻辑            //        }        #region IHttpModule 成员        public void Dispose()        {        }        public void Init(HttpApplication context)        {            context.PreRequestHandlerExecute += 
                              new EventHandler(context_PreRequestHandlerExecute);            context.PostRequestHandlerExecute += 
                              new EventHandler(context_PostRequestHandlerExecute);        }        void context_PreRequestHandlerExecute(object sender, EventArgs e)        {            HttpApplication context = sender as HttpApplication;            IHttpHandler httpHandler = context.Context.CurrentHandler;            if (httpHandler is ISingleLogin)            {                ISingleLogin sl = httpHandler as ISingleLogin;                string suid = sl.SigleUserLoginId;                if (suid != string.Empty)                {                    if (PreLogoutSessionIdDictionary.
                                            ContainsKey(context.Session.SessionID))                    {                        //这个用户应该强制登出                        PreLogoutSessionIdDictionary.Remove(context.Session.SessionID);                        Page page = (Page) httpHandler;                        page.PreInit += new EventHandler(page_PreInit);                    }                    else if (!LoginedUserIdDictionary.ContainsKey(suid))                    {                        LoginedUserIdDictionary.Add(suid,
                                          new LifeValue(context.Session.SessionID));                    }                }            }        }        void page_PreInit(object sender, EventArgs e)        {            Page page = sender as Page;            ISingleLogin sl = page as ISingleLogin;            if (sl != null)            {                sl.SigleUserLogout();                page.Response.End();            }        }        void context_PostRequestHandlerExecute(object sender, EventArgs e)        {            //从LogineduserId 里找到和当前用户一样的用户ID的SessionId            HttpApplication context = sender as HttpApplication;            IHttpHandler httpHandler = context.Context.CurrentHandler;            if (httpHandler is ISingleLogin)            {                ISingleLogin sl = httpHandler as ISingleLogin;                string suid = sl.SigleUserLoginId;                if (suid != string.Empty)                {                    if (LoginedUserIdDictionary.ContainsKey(suid))                    {                        string sessionId = LoginedUserIdDictionary[suid].value;                        if (sessionId != context.Session.SessionID)                        {                            if (!PreLogoutSessionIdDictionary.ContainsKey(sessionId))                            {                                PreLogoutSessionIdDictionary.
                                               Add(sessionId, new LifeValue(suid));                            }                            LoginedUserIdDictionary.Remove(suid);                        }                    }                    else                    {                        LoginedUserIdDictionary.Add(sl.SigleUserLoginId, 
                       new LifeValue(context.Session.SessionID));                    }                }            }        }        #endregion    }    public class LifeValue    {        public string value;        public DateTime life;        public LifeValue(string value)        {            this.value = value;            this.life = DateTime.Now.AddMinutes(HttpContext.Current.
             Session.Timeout + 5);        }    }    public class StringLifeValueDictionary : Dictionary<string, LifeValue>    {    }    public interface ISingleLogin    {        string SigleUserLoginId { get; }        void SigleUserLogout();    }}