Asp.net中实现同一用户名不能同时登陆(单点登陆)

Web项目中经常遇到的问题就是同一用户名多次登陆的问题，相应的解决办法也很多，总结起来不外乎这几种解决办法：将登陆后的用户名放到数据库表中；登陆后的用户名放到Session中；登陆后的用户名放到Application中；登陆后的用户名放到Cache中。一般的这几种方法都是登陆了之后，如果没有正常退出，第二次登陆将不被允许。这样一般都会存在一个问题：如果用户没有正常退出系统，那么他接下来继续登陆的时候，因为Session没有过期等问题，会被拒绝继续登陆系统，只能等待Session过期后才能登陆。本文介绍的方法是采用类似于MSN登陆的方法，第二次登陆时会把第一次的登陆注销掉，第一次登陆将会类似于MSN弹出：您的帐号已在别处被登陆，您被强迫下线的提示信息。



功能实现起来也比较简单：



登陆用户名密码验证通过之后输入以下代码：

-Page_Separating achieve the same user name can not landing (single-point landing) Web projects often encountered The problem is the same user name repeatedly landing problems, the corresponding solutions are many, This sum up no more than several solutions : After landing the user into database tables; After making landfall, the user into Session; After making landfall, the user into Application; After making landfall, the user into Cache. General these methods are after landing, in the absence of normal withdrawal, the second landing would not be allowed. This will usually there's a problem : If users are not withdraw from the normal system, then followed him to the landing, Session expired because no such problems will continue to be refused landing system, we can only wait until the