ASP.NET在線用戶列表精確版——解決用戶意外退出在線列表無法及時更新問題

2019-11-17 05:25:05

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來源：轉載

供稿：網友

【原創作者】：叢興滋（cncxz）[E-mail：cncxz@126.com]
【關鍵詞】：xmlhttp asp.net在線用戶列表關閉瀏覽器精確統計單人登陸
【代碼下載】：http://www.thisky.cn/down/onlineuser.rar    最近所做的一個項目需要用到的在線用戶列表，上網搜索了一下發現現有的解決方案對用戶意外退出的處理均不是太理想。一般來說，用戶離開系統的方式有三種：主動注銷、會話超時、直接關閉瀏覽器，對于前兩種，我們很輕易便可將該用戶從在線列表中清除，要害是第三種（很多用戶都是直接關閉窗口的~~郁悶ing），程序無法捕捉窗口關閉的精確時間，只能等到會話超時后在能將該用戶清除出在線列表，假設我們設置會話超時時間為60分鐘，而用戶登陸系統隨便瀏覽一個頁面就以關閉瀏覽器的方式退出的話，我們要在將近1小時后才能從在線列表中將該用戶清除出去（想象一下，系統顯示n多人在線，可能除了你之外其他的n-1人都關機走人了，汗一個先```），而本文將嘗試尋找一個解決方案把這種尷尬降至最低。
    我的大概思路是，給每在線用戶增加一個RefreshTime屬性，建立一個負責將當前用戶的RefreshTime屬性設置為當前時間的單獨頁面（Refresh.ASPx），然后在系統的主要頁面（也可以是所有頁面）中通過xmlhttp不斷地請求Refresh.aspx頁面，一旦用戶關閉了與本系統相關的所有窗口，即以直接關閉瀏覽器的方式退出系統，那么該用戶的RefreshTime屬性便不會自動更新了，我們再設置一個自動刷新的超時時間（這個要比會話超時短很多_refreshTimeout），當發現某用戶超過_refreshTimeout的時間沒有自動刷新，就能判定該用戶已經以直接關閉瀏覽器的方式退出了。
    假設我們設置會話超時時間為60分鐘，自動刷新超時時間為1分鐘，在客戶端通過xmlhttp每隔25秒（之所以不設1分鐘，是防止網速慢的時候訪問Refresh.aspx超時，個人感覺，不一定正確）訪問一次Refresh.aspx頁面，在用戶登陸、用戶注銷、檢測用戶是否在線的時候都執行清理超時用戶（包括會話超時和自動刷新超時）操作，這樣一來，在線用戶列表的統計誤差就由60分鐘降至1分鐘了。==========================================

具體實現如下：
1、新建一個名為ActiveUser的類，存儲單個活動用戶數據。
/// <summary>
/// 單個在線用戶數據，無法繼續此類。
/// </summary>
public sealed class ActiveUser
{
  PRivate readonly string _ticket;    //票據名稱
  private readonly string _username;   //登陸用戶名
  private readonly string _truename;   //登陸用戶名
  private readonly string _roleid;    //角色
  private readonly DateTime _refreshtime;  //最新刷新時間
  private readonly DateTime _activetime;  //最新活動時間
  private readonly string _clientip;   //登陸IP

  public ActiveUser(string Ticket,string UserName,string TrueName,string RoleID,string ClientIP) {
   this._ticket=Ticket;
   this._username=UserName;
   this._truename=TrueName;
   this._roleid=RoleID;
   this._refreshtime=DateTime.Now;
   this._activetime=DateTime.Now;
   this._clientip=ClientIP;
  }  public ActiveUser(string Ticket,string UserName,string TrueName,string RoleID,DateTime RefreshTime,DateTime ActiveTime,string ClientIP)  {
   this._ticket=Ticket;
   this._username=UserName;
   this._truename=TrueName;
   this._roleid=RoleID;
   this._refreshtime=RefreshTime;
   this._activetime=ActiveTime;
   this._clientip=ClientIP;
  }

  public string Ticket  { get{return _ticket;}  }
  public string UserName  { get{return _username;}  }
  public string TrueName  { get{return _truename;}  }
  public string RoleID  { get{return _roleid;}  }
  public DateTime RefreshTime { get{return _refreshtime;} }
  public DateTime ActiveTime { get{return _activetime;} }
  public string ClientIP  { get{return _clientip;}  }
}
2、新建一個名為PassPort的類，存儲在線用戶列表。/// <summary>
/// 單個在線用戶數據，無法繼續此類。
/// </summary>
public sealed class ActiveUser
{
  private readonly string _ticket;    //票據名稱
  private readonly string _username;   //登陸用戶名
  private readonly string _truename;   //登陸用戶名
  private readonly string _roleid;    //角色
  private readonly DateTime _refreshtime;  //最新刷新時間
  private readonly DateTime _activetime;  //最新活動時間
  private readonly string _clientip;   //登陸IP

  public ActiveUser(string Ticket,string UserName,string TrueName,string RoleID,string ClientIP) {
   this._ticket=Ticket;
   this._username=UserName;
   this._truename=TrueName;
   this._roleid=RoleID;
   this._refreshtime=DateTime.Now;
   this._activetime=DateTime.Now;
   this._clientip=ClientIP;
  }  public ActiveUser(string Ticket,string UserName,string TrueName,string RoleID,DateTime RefreshTime,DateTime ActiveTime,string ClientIP)  {
   this._ticket=Ticket;
   this._username=UserName;
   this._truename=TrueName;
   this._roleid=RoleID;
   this._refreshtime=RefreshTime;
   this._activetime=ActiveTime;
   this._clientip=ClientIP;
  }

  public string Ticket  { get{return _ticket;}  }
  public string UserName  { get{return _username;}  }
  public string TrueName  { get{return _truename;}  }
  public string RoleID  { get{return _roleid;}  }
  public DateTime RefreshTime { get{return _refreshtime;} }
  public DateTime ActiveTime { get{return _activetime;} }
  public string ClientIP  { get{return _clientip;}  } }
2、新建一個名為PassPort的類，存儲在線用戶列表。/// <summary>
/// 單個在線用戶數據，無法繼續此類。
/// </summary>
public sealed class ActiveUser
{
  private readonly string _ticket;    //票據名稱
  private readonly string _username;   //登陸用戶名
  private readonly string _truename;   //登陸用戶名
  private readonly string _roleid;    //角色
  private readonly DateTime _refreshtime;  //最新刷新時間
  private readonly DateTime _activetime;  //最新活動時間
  private readonly string _clientip;   //登陸IP

  public ActiveUser(string Ticket,string UserName,string TrueName,string RoleID,string ClientIP) {
   this._ticket=Ticket;
   this._username=UserName;
   this._truename=TrueName;
   this._roleid=RoleID;
   this._refreshtime=DateTime.Now;
   this._activetime=DateTime.Now;
   this._clientip=ClientIP;
  }
  public ActiveUser(string Ticket,string UserName,string TrueName,string RoleID,DateTime RefreshTime,DateTime ActiveTime,string ClientIP)  {
   this._ticket=Ticket;
   this._username=UserName;
   this._truename=TrueName;
   this._roleid=RoleID;
   this._refreshtime=RefreshTime;
   this._activetime=ActiveTime;
   this._clientip=ClientIP;
  }

  public string Ticket  { get{return _ticket;}  }
  public string UserName  { get{return _username;}  }
  public string TrueName  { get{return _truename;}  }
  public string RoleID  { get{return _roleid;}  }
  public DateTime RefreshTime { get{return _refreshtime;} }
  public DateTime ActiveTime { get{return _activetime;} }
  public string ClientIP  { get{return _clientip;}  } }
2、新建一個名為PassPort的類，存儲在線用戶列表。/// <summary>
/// PassPort 存儲在線用戶列表。
/// </summary>
public class PassPort
{
  private static DataTable _activeusers;
  private int _activeTimeout;
  private int _refreshTimeout;  /// <summary>
  /// 初始化在線用戶表。
  /// </summary>
  private void userstableFormat()
  {
   if(_activeusers==null) {
    _activeusers = new DataTable("ActiveUsers");
    DataColumn myDataColumn;
    System.Type mystringtype;
    mystringtype = System.Type.GetType("System.String");
    System.Type mytimetype;
    mytimetype = System.Type.GetType("System.DateTime");
    myDataColumn = new DataColumn("Ticket",mystringtype);
    _activeusers.Columns.Add(myDataColumn);
    myDataColumn = new DataColumn("UserName",mystringtype);
    _activeusers.Columns.Add(myDataColumn);
    myDataColumn = new DataColumn("TrueName",mystringtype);
    _activeusers.Columns.Add(myDataColumn);
    myDataColumn = new DataColumn("RoleID",mystringtype);
    _activeusers.Columns.Add(myDataColumn);
    myDataColumn = new DataColumn("RefreshTime",mytimetype);
    _activeusers.Columns.Add(myDataColumn);
    myDataColumn = new DataColumn("ActiveTime",mytimetype);
    _activeusers.Columns.Add(myDataColumn);
    myDataColumn = new DataColumn("ClientIP",mystringtype);
    _activeusers.Columns.Add(myDataColumn);
   }
  }
  public PassPort()
  {
   userstableFormat(); //初始化在線用戶表
   //活動超時時間初始化單位：分鐘
   try { _activeTimeout=int.Parse(ConfigurationSettings.AppSettings["ActiveTimeout"]); }
   catch{ _activeTimeout=60; }
   //自動刷新超時時間初始化單位：分鐘
   try { _refreshTimeout=int.Parse(ConfigurationSettings.AppSettings["RefreshTimeout"]); }
   catch{ _refreshTimeout=1; }
  }  //全部用戶列表
  public DataTable ActiveUsers
  {
   get{return _activeusers.Copy();}
  }

  /// <summary>
  /// 新用戶登陸。
  /// </summary>
  public void Login(ActiveUser user,bool SingleLogin)
  {
   DelTimeOut();  //清除超時用戶
   if(SingleLogin){
    //若是單人登陸則注銷原來登陸的用戶
    this.Logout(user.UserName,false);
   }
   DataRow myRow;
   try
   {
    myRow = _activeusers.NewRow();
    myRow["Ticket"] = user.Ticket.Trim();
    myRow["UserName"] = user.UserName.Trim();
    myRow["TrueName"] = ""+user.TrueName.Trim();
    myRow["RoleID"] = ""+user.RoleID.Trim();
    myRow["ActiveTime"] = DateTime.Now;
    myRow["RefreshTime"] = DateTime.Now;
    myRow["ClientIP"] = user.ClientIP.Trim();
    _activeusers.Rows.Add(myRow);
   }
   catch(Exception e)
   {
    throw(new Exception(e.Message));
   }
   _activeusers.AcceptChanges();

  }  /// <summary>
  ///用戶注銷，根據Ticket或UserName。
  /// </summary>
  private void Logout(string strUserKey,bool byTicket)
  {
   DelTimeOut();  //清除超時用戶
   strUserKey=strUserKey.Trim();
   string strEXPr;
   strExpr =byTicket ? "Ticket='" + strUserKey +"'" : "UserName='" + strUserKey + "'";
   DataRow[] curUser;
   curUser = _activeusers.Select(strExpr);
   if (curUser.Length >0 )
   {
    for(int i = 0; i < curUser.Length; i ++)
    {
     curUser[i].Delete();
    }
   }
   _activeusers.AcceptChanges();
  }
  /// <summary>
  ///用戶注銷，根據Ticket。
  /// </summary>
  /// <param name="strTicket">要注銷的用戶Ticket</param>
  public void Logout(string strTicket){
   this.Logout(strTicket,true);
  }  /// <summary>
  ///清除超時用戶。
  /// </summary>
  private bool DelTimeOut()
  {
   string strExpr;
   strExpr = "ActiveTime < '" + DateTime.Now.AddMinutes( 0 - _activeTimeout) + "'or RefreshTime < '"+DateTime.Now.AddMinutes( 0 - _refreshTimeout)+"'";
   DataRow[] curUser;
   curUser = _activeusers.Select(strExpr);
   if (curUser.Length >0 )
   {
    for(int i = 0; i < curUser.Length; i ++)
    {
     curUser[i].Delete();
    }
   }
   _activeusers.AcceptChanges();
   return true;
  }  /// <summary>
  ///更新用戶活動時間。
  /// </summary>
  public void ActiveTime(string strTicket)
  {
   DelTimeOut();
   string strExpr;
   strExpr = "Ticket='" + strTicket + "'";
   DataRow[] curUser;
   curUser = _activeusers.Select(strExpr);
   if (curUser.Length >0 )
   {
    for(int i = 0; i < curUser.Length; i ++)
    {
     curUser[i]["ActiveTime"]=DateTime.Now;
     curUser[i]["RefreshTime"]=DateTime.Now;
    }
   }
   _activeusers.AcceptChanges();
  }  /// <summary>
  ///更新系統自動刷新時間。
  /// </summary>
  public void RefreshTime(string strTicket)
  {
   DelTimeOut();
   string strExpr;
   strExpr = "Ticket='" + strTicket + "'";
   DataRow[] curUser;
   curUser = _activeusers.Select(strExpr);
   if (curUser.Length >0 )
   {
    for(int i = 0; i < curUser.Length; i ++)
    {
     curUser[i]["RefreshTime"]=DateTime.Now;
    }
   }
   _activeusers.AcceptChanges();
  }
  private ActiveUser SingleUser(string strUserKey,bool byTicket)
  {
   strUserKey=strUserKey.Trim();
   string strExpr;
   ActiveUser myuser;
   strExpr =byTicket ? "Ticket='" + strUserKey +"'" : "UserName='" + strUserKey + "'";
   DataRow[] curUser;
   curUser = _activeusers.Select(strExpr);
   if (curUser.Length >0 )
{
    string myTicket=(string)curUser[0]["Ticket"];
    string myUser=(string)curUser[0]["UserName"];
    string myName=(string)curUser[0]["TrueName"];
    string myRoleID=(string)curUser[0]["RoleID"];
    DateTime myActiveTime=(DateTime)curUser[0]["ActiveTime"];
    DateTime myRefreshtime=(DateTime)curUser[0]["RefreshTime"];
    string myClientIP =(string)curUser[0]["ClientIP"];
    myuser=new ActiveUser(myTicket,myUser,myName,myRoleID,myActiveTime,myRefreshtime,myClientIP);
   }
   else
   {
    myuser=new ActiveUser("","","","","");
   }
   return myuser;
  }  /// <summary>
  ///按Ticket獲取活動用戶。
  /// </summary>
  public ActiveUser SingleUser_byTicket(string strTicket)
  {
   return this.SingleUser(strTicket,true);
  }  /// <summary>
  ///按UserName獲取活動用戶。
  /// </summary>
  public ActiveUser SingleUser_byUserName(string strUserName)
  {
   return this.SingleUser(strUserName,false);
  }  /// <summary>
  ///按Ticket判定用戶是否在線。
  /// </summary>
  public bool IsOnline_byTicket(string strTicket)
  {
   return (bool)(this.SingleUser(strTicket,true).UserName!="");
  }  /// <summary>
  ///按UserName判定用戶是否在線。
  /// </summary>
  public bool IsOnline_byUserName(string strUserName)
  {
   return (bool)(this.SingleUser(strUserName,false).UserName!="");
  }
}
3、新建一個繼續自PlaceHolder名為Refresh的類，執行更新自動刷新時間操作。
/// <summary>
/// Refresh 執行更新自動刷新時間操作。
/// </summary>
public class Refresh: PlaceHolder
{
  /// <summary>
  /// 設置存儲Ticket的session名稱，默認為Ticket。
  /// </summary>
  public virtual string SessionName
  {
   get{
    object obj1 = this.ViewState["SessionName"];
    if (obj1 != null){ return ((string) obj1).Trim(); }
    return "Ticket";
   }
   set{
    this.ViewState["SessionName"] = value;
   }
  }
  protected override void Render(HtmlTextWriter writer)
  {
   string myTicket=(string)this.Page.Session[this.SessionName];
   if(myTicket!=null)
   {
    PassPort myPass = new PassPort();
    myPass.RefreshTime(myTicket);
    writer.Write("OK："+DateTime.Now.ToString());
   }
   else{
    writer.Write("Sorry："+DateTime.Now.ToString());
   }
   base.Render(writer);
}
}4、新建一個繼續自PlaceHolder名為Script的類，生成執行xmlhttp的js腳本。。
/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""javascript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""Javascript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。/// <summary>
/// Refresh 執行更新自動刷新時間操作。
/// </summary>
public class Refresh: PlaceHolder
{
  /// <summary>
  /// 設置存儲Ticket的Session名稱，默認為Ticket。
  /// </summary>
  public virtual string SessionName
  {
   get{
    object obj1 = this.ViewState["SessionName"];
    if (obj1 != null){ return ((string) obj1).Trim(); }
    return "Ticket";
   }
   set{
    this.ViewState["SessionName"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   string myTicket=(string)this.Page.Session[this.SessionName];
   if(myTicket!=null)
   {
    PassPort myPass = new PassPort();
    myPass.RefreshTime(myTicket);
    writer.Write("OK："+DateTime.Now.ToString());
   }
   else{
    writer.Write("Sorry："+DateTime.Now.ToString());
   }
   base.Render(writer);
}
}4、新建一個繼續自PlaceHolder名為Script的類，生成執行xmlhttp的js腳本。。
/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""JavaScript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""JavaScript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。
3、新建一個繼續自PlaceHolder名為Refresh的類，執行更新自動刷新時間操作。
/// <summary>
/// Refresh 執行更新自動刷新時間操作。
/// </summary>
public class Refresh: PlaceHolder
{
  /// <summary>
  /// 設置存儲Ticket的Session名稱，默認為Ticket。
  /// </summary>
  public virtual string SessionName
  {
   get{
    object obj1 = this.ViewState["SessionName"];
    if (obj1 != null){ return ((string) obj1).Trim(); }
    return "Ticket";
   }
   set{
    this.ViewState["SessionName"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   string myTicket=(string)this.Page.Session[this.SessionName];
   if(myTicket!=null)
   {
    PassPort myPass = new PassPort();
    myPass.RefreshTime(myTicket);
    writer.Write("OK："+DateTime.Now.ToString());
   }
   else{
    writer.Write("Sorry："+DateTime.Now.ToString());
   }
   base.Render(writer);
}
}4、新建一個繼續自PlaceHolder名為Script的類，生成執行xmlhttp的js腳本。。
/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""JavaScript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""JavaScript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。4、新建一個繼續自PlaceHolder名為Script的類，生成執行xmlhttp的js腳本。。
/// <summary>
/// Script 生成執行xmlhttp的js腳本。
/// </summary>
public class Script: PlaceHolder
{
  /// <summary>
  /// 設置js自動刷新的間隔時間，默認為25秒。
  /// </summary>
  public virtual int RefreshTime
  {
   get
   {
    object obj1 = this.ViewState["RefreshTime"];
    if (obj1 != null){return int.Parse(((string) obj1).Trim());}
    return 25;
   }
   set
   {
    this.ViewState["RefreshTime"] = value;
   }
  }  protected override void Render(HtmlTextWriter writer)
  {
   //從web.config中讀取xmlhttp的訪問地址
   string refreshUrl=(string)ConfigurationSettings.AppSettings["refreshUrl"];
   string scriptString = @" <script language=""JavaScript"">"+writer.NewLine;
   scriptString += @"  window.attachEvent(""onload"", "+this.ClientID+@"_postRefresh);"+writer.NewLine;
   scriptString += @"  var "+this.ClientID+@"_xmlhttp=null;"+writer.NewLine;
   scriptString += @"  function "+this.ClientID+@"_postRefresh(){"+writer.NewLine;
   scriptString += @"   var "+this.ClientID+@"_xmlhttp = new ActiveXObject(""Msxml2.XMLHTTP"");"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Open(""POST"", """+refreshUrl+@""", false);"+writer.NewLine;
   scriptString += @"   "+this.ClientID+@"_xmlhttp.Send();"+writer.NewLine;
   scriptString += @"   var refreshStr= "+this.ClientID+@"_xmlhttp.responseText;"+writer.NewLine;

   scriptString += @"   try {"+writer.NewLine;
   scriptString += @"    var refreshStr2=refreshStr;"+writer.NewLine;
   //scriptString += @"    alert(refreshStr2);"+writer.NewLine;
   scriptString += @"   }"+writer.NewLine;
   scriptString += @"   catch(e) {}"+writer.NewLine;
   scriptString += @"   setTimeout("""+this.ClientID+@"_postRefresh()"","+this.RefreshTime.ToString()+@"000);"+writer.NewLine;
   scriptString += @"  }"+writer.NewLine;
   scriptString += @"<";
   scriptString += @"/";
   scriptString += @"script>"+writer.NewLine;
   writer.Write(writer.NewLine);
   writer.Write(scriptString);
   writer.Write(writer.NewLine);
   base.Render(writer);
  }
}
注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。注重以上四個類同屬于一個名為OnlineUser的工程，他們的命名空間為OnlineUser，編譯生成一個dll。===============================================
下面我簡單介紹一下調用方法：1、新建一個名為OnlineUserDemo的asp.net web應用程序
2、在vs的工具箱選項卡上右擊，選擇[添加/移除項]，瀏覽定位到OnlineUser.dll，確定即可把Refresh 和Script添加到工具箱。
3、把自動生成的WebForm1.aspx刪除，并設置web.config
<appSettings>
   <add key="ActiveTimeout" value="30" />
   <add key="RefreshTimeout" value="1" />
   <add key="refreshUrl" value="refresh.aspx" />
</appSettings>
4、添加一個名為Online.aspx的web窗體，給該窗體添加一個Script控件，一個DataGrid控件（id為DataGrid1），兩個HyperLink控件（分別鏈接到login.aspx和logout.aspx，text屬性分別設置為“登陸”和“注銷”），調整好四個控件的位置，轉到codebehind，在Page_Load中加入如下代碼：
string myTicket=(string)this.Page.Session["Ticket"];
   if(myTicket!=null)
   {
    OnlineUser.PassPort myPassPort= new OnlineUser.PassPort();
    if(myPassPort.IsOnline_byTicket(this.Session["Ticket"].ToString()))
    {
     myPassPort.ActiveTime(this.Session["Ticket"].ToString());
     DataGrid1.DataSource=myPassPort.ActiveUsers;
     DataGrid1.DataBind();
    }
    else{
     //若在線用戶列表中找不到當前用戶,則定向到注銷頁面
     Response.Redirect("Logout.aspx");
    }
   }
   else{
    Response.Redirect("Login.aspx");
   }
5、添加一個名為login.aspx的web窗體，給該窗體添加一個label控件（id為Label1），設置text屬性為“輸入一個用戶名”，再添加一個textbox控件（id為TextBox1）和一個button控件（id為Button1），調整好他們的位置，雙擊Button1控件轉到codebehind，為Button1的Click事件加入如下代碼：
if(TextBox1.Text.Trim()=="")
   {
    //不能為空
    String scriptString = @"<script language=JavaScript>";
    scriptString += @"alert(""輸入一個用戶名/n"");";
    scriptString += @"history.go(-1);";
    scriptString += @"<";
    scriptString += @"/";
    scriptString += @"script>";
    if(!this.Page.IsStartupScriptRegistered("Startup"))
     this.Page.RegisterStartupScript("Startup", scriptString);
   }
   else{
    OnlineUser.PassPort myPassPort= new OnlineUser.PassPort();
    string myTicket=DateTime.Now.ToString("yyyyMMddHHmmss");
    string myUser=TextBox1.Text.Trim();
    string myClintIP=this.Request.UserHostAddress;
    this.Session["Ticket"]=myTicket;
    OnlineUser.ActiveUser myActiveUser=new OnlineUser.ActiveUser(myTicket,myUser,myUser,"test",myClintIP);
    myPassPort.Login(myActiveUser,true);
    Response.Redirect("Online.aspx");
   }
6、添加一個名為logout.aspx的web窗體，給該窗體添加一個HyperLink控件，指向login.aspx，text屬性設置為“重登陸”轉到codebehind，在Page_Load中加入如下代碼：
OnlineUser.PassPort myPassPort= new OnlineUser.PassPort();
  myPassPort.Logout(this.Session["Ticket"].ToString());
this.Session["Ticket"]="";
7、添加一個名為Refresh.txt的文本文件，設置其內容為：
<%@ Register TagPrefix="cc2" Namespace="OnlineUser" Assembly="OnlineUser" %>
<%@ Page %>
<cc2:Refresh id="myRefresh" runat="server"></cc2:Refresh>
把Refresh.txt改名為Refresh.aspx8、編譯生成工程。===============================================
下面進行功能測試：

1、打開瀏覽器，在地址欄輸入
http://你機器的IP地址/onlineuserdemo/Login.aspx
2、輸入一個用戶名（假設是test1）登陸，自動轉到online.aspx頁面
3、找同網段的另外一臺機器（設你的機器為a，這臺機器為b），重復執行第一步。
4、輸入一個用戶名（假設是test2）登陸，自動轉到online.aspx頁面
5、在b機器不斷刷新online.aspx，若發現test1用戶RefreshTime每過25秒自動更新一次而ActiveTime不變（這個時候a機器不要刷新頁面啊），則證實a機器的自動刷新生效。
6、在a機器不斷刷新online.aspx，若發現test2用戶RefreshTime每過25秒自動更新一次而ActiveTime不變（這個時候b機器不要刷新頁面啊），則證實b機器的自動刷新生效。
7、大功告成。==========================================================附：網上現有的一些在線人數統計的文章

ASP.NET 在線用戶列表
http://www.mscenter.edu.cn/blog/jeffrey/archive/2005/03/25/1024.html
如何顯示在線人數和所在位置
http://www.7880.com/Info/Article-40c2aca0.html
不用Golobal.asa和session實現在線人數統計
http://www.7880.com/Info/Article-31034d60.html
利用文件屬性結合Session實現在線人數統計
http://www.7880.com/Info/Article-2b369f40.html
網站當前的在線人數
http://www.7880.com/Info/Article-2a6d34c0.html
基于數據庫的在線人數，日訪問量等統計
http://www.7880.com/Info/Article-29f01580.html
網頁在線人數統計的做法
http://www.7880.com/Info/Article-1d4ebf20.html
不用Global.asa實現在線人數統計
http://www.7880.com/Info/Article-1c09bc00.html
如何實現網頁在線人數統計
http://www.7880.com/Info/Article-12bd5d00.html
兩種統計當前在線人數的方法
http://www.7880.com/Info/Article-af79e0.html

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