同一账号禁止多人同时登陆

首先在Global中写如下代码:

protected void Session_Start(Object sender, EventArgs e)
 ...{
 ArrayList lstName=new ArrayList();
 this.Application.Add("name",lstName);
 }

 //****************************************************************************************************8
 protected void Session_End(Object sender, EventArgs e)
 ...{
 Application.Lock();
 string str=Session["name"].ToString();
 ArrayList lstName=(ArrayList)this.Application["name"];
 Application.UnLock();
 }

然后在登陆页面写代码

string username=this.txtName.Text.Trim();
 ArrayList lstName=(ArrayList)this.Application["name"];
 foreach(string strname in lstName)
 ...{
 if(username.Equals(strname))
 ...{
 Response.Redirect("User_Login.aspx");
 }
 }

 lstName=(ArrayList)Application["name"];
 lstName.Add(this.txtName.Text.Trim());
 this.Application.Lock();
 this.Application["name"]=lstName;
 Session["name"]=username;
 this.Application.UnLock();
 this.Response.Redirect("main.aspx");