asp.Net次のアカウントでは、複数のユーザーが同時にオンラインで、繰り返しログインするコードは許可されていません.

方法1:

 
  
string sKey = username.Text.ToString().Trim(); //   Cache    Key   
  
string sUser = Convert.ToString(Cache[sKey]); //        
  
if (sUser == null || sUser == String.Empty) 
  
{ 
  
TimeSpan SessTimeOut = new TimeSpan(0, 0, System.Web.HttpContext.Current.Session.Timeout, 0, 0);//  Session      
  
HttpContext.Current.Cache.Insert(sKey, sKey, null, DateTime.MaxValue, SessTimeOut, System.Web.Caching.CacheItemPriority.NotRemovable, null);//    cache        
  
//     
  
} 
  
else if (Cache[sKey].ToString() == sKey)//           
  
{ 
  
ClientScript.RegisterStartupScript(GetType(), "  ", "alert('   ,        ');"); 
  
return; 
  
} 
  
else 
  
{ 
  
Session.Abandon();//                      
  
} 
  
 
 

 
  
//           Cache   .    aspx       onunload  .  ajax  hOnline  Session.SessionID 
  
window.onunload=function(){ 
  
$.ajax({ 
  
type: "POST", 
  
　　　data:"sKey="+sKey; 
  
url: "online.aspx" 
  
}); 
  
} 
  
 
 

online.aspx.csコード

 
  
protected void Page_Load(object sender, EventArgs e) 
  
{ 
  
　　　　HttpContext.Current.Cache.Remove(sKey); 
  
} 
  
// Global.asax    Session_End      
  
//Session   .  hOnline  Session.SessionID 
  
　　　　Hashtable hOnline = (Hashtable)Application["Online"]; 
  
if (hOnline[Session.SessionID] != null) 
  
{ 
  
hOnline.Remove(Session.SessionID); 
  
Application.Lock(); 
  
Application["Online"] = hOnline; 
  
Application.UnLock(); 
  
} 
  
 
 

方法2:

 
  
//sKey       
  
if(ApplicationOnline(username.Text.tirm())){ 
  
Hashtable hOnline = new Hashtable(); 
  
hOnline[Session.SessionID] = sKey; 
  
Application.Lock(); 
  
Application["Online"] = hOnline; 
  
Application.UnLock(); 
  
} 
  
 
  
public Boolean ApplicationOnline(string sKey) 
  
{ 
  
Boolean flag = true; 
  
Hashtable hOnline = (Hashtable)Application["Online"]; 
  
if (hOnline != null) 
  
{ 
  
IDictionaryEnumerator idE = hOnline.GetEnumerator(); 
  
while (idE.MoveNext()) 
  
{ 
  
//if (idE.Key != null && idE.Key.ToString().Equals(Session.SessionID)) 
  
//{ 
  
if (idE.Value != null && sKey.Equals(idE.Value.ToString())) 
  
{ 
  
flag = false; 
  
} 
  
break; 
  
//} 
  
} 
  
} 
  
return flag; 
  
} 
  
 
  
//           Session.SessionID   .    aspx       onunload  .  ajax  Session.SessionID 
  
window.onunload=function(){ 
  
$.ajax({ 
  
type: "POST", 
  
url: "online.aspx" 
  
}); 
  
} 
  
 
 

online.aspx.csコード

 
  
protected void Page_Load(object sender, EventArgs e) 
  
{ 
  
Hashtable hOnline = (Hashtable)Application["Online"]; 
  
if (hOnline[Session.SessionID] != null) 
  
{ 
  
hOnline.Remove(Session.SessionID); 
  
Application.Lock(); 
  
Application["Online"] = hOnline; 
  
Application.UnLock(); 
  
} 
  
}