ASP.NET C# 实现实时用户在线

public static class UserOnline
{
/// <summary>
/// 获取或设置在线列表
/// </summary>
public static Hashtable OnlineUserList
{
get
{
if (HttpContext.Current.Application["OnlineUserList"] == null)
{
Hashtable onlineUserList = new Hashtable();
HttpContext.Current.Application["OnlineUserList"] = onlineUserList;
}

return (Hashtable)HttpContext.Current.Application["OnlineUserList"];
}
set
{
HttpContext.Current.Application["OnlineUserList"] = value;
}
}

/// <summary>
/// 添加在线成员
/// </summary>
public static bool OnlineUserList_Add(string key, string value)
{
try
{
if (OnlineUserList.Contains(key))
OnlineUserList[key] = value;
else
OnlineUserList.Add(key, value);
return true;
}
catch
{
return false;
}
}

/// <summary>
/// 添加在线成员
/// </summary>
public static bool OnlineUserList_Add(string key)
{
string value = DateTime.Now.ToString();
return OnlineUserList_Add(key, value);
}

/// <summary>
/// 离线删除用户
/// </summary>
public static bool OnlineUserList_Delete(string key)
{
bool re = false;
if (OnlineUserList.Contains(key))
{
Hashtable userList = OnlineUserList;
userList.Remove(key);
OnlineUserList = userList;
return true;
}
return re;
}

/// <summary>
/// 判断用户是否在线
/// </summary>
public static bool UserIsOnline(string adminName)
{
OnlineClearUserOutTimeInOnLineList();
return OnlineUserList.Contains(adminName) ? true : false;
}

/// <summary>
/// 删除超时在线用户
/// </summary>
public static void OnlineClearUserOutTimeInOnLineList()
{
int OnlineTimeOut = 20;
Hashtable list = new Hashtable();
Hashtable temList = new Hashtable();
list = OnlineUserList;
temList = new Hashtable(list);
foreach (DictionaryEntry de in temList)
{
//删除超时
DateTime onlineTime = Convert.ToDateTime(de.Value);
TimeSpan timeSpan = DateTime.Now - onlineTime;

//在线时间和当前时间间隔大于超时分钟数就删除(注：用户非法关闭浏览器)
if (timeSpan.TotalMinutes >= (double)OnlineTimeOut)
{
list.Remove(de.Key);
}

}

OnlineUserList = list;
}

}