防止session失效的最佳效果

　　很多时候用到Session都比较厌烦，主要还因为很容易就丢失了！
　　解决的方法有：
　　1、设置Session时间；
　　在Global.ascx文件中的设置时间： Session.Timeout = 600;

　　2、放在服务器里：
　　web.config中配置 <sessionstate mode="stateServer">后，在服务中启动 asp.net state service (asp.net状态服务)
　　除了以上两种方法外，就是Session + Cookies ！双重保险。废话不多说，直接看代码就知道了：

public static bool Islogin(string Uname, string Pwd, bool writecookie)
{
    bool brt = false;
    com.csfqw.passport.API wsLogin = new NT.Data.SqlServer.com.csfqw.passport.API();
    DataSet ds = wsLogin.IsLogin(Uname, Pwd);

    if (ds.Tables[0].Rows.Count > 0)
    {
        DataRow dr = ds.Tables[0].Rows[0];
        System.Web.HttpContext.Current.Session["username"] = dr["username"].ToString();
        brt = true;
        if (writecookie)
        {
            NTCookies cookie = new NTCookies("NetUser");
            cookie.WriteCookie("username", Uname);
            cookie.SetExpires(60);
            cookie.Domain = "csfqw.com";
            cookie.RespnseCookies();
            brt = true;
        }
    }
    return brt;
}

public static void UserLoginOut()
{
    //NTCookies cookie = new NTCookies("NetUser");
    //cookie.ClearCookies();
    //HttpContext.Current.Session.Remove("username");

    ///退出用户
    HttpCookie cookie =System.Web.HttpContext.Current.Request.Cookies["NetUser"];
    if (cookie != null && cookie["username"] != null)
    {
        cookie.Expires = DateTime.Now.AddDays(-1.0d);
        cookie.Domain = "csfqw.com";
        System.Web.HttpContext.Current.Response.AppendCookie(cookie);
    }

    ///撤销专家
    HttpCookie expertcookie = System.Web.HttpContext.Current.Request.Cookies["IsExpert"];
    if (expertcookie != null && expertcookie["Expert"] != null)
    {
        expertcookie.Expires = DateTime.Now.AddDays(-1.0d);
        expertcookie.Domain = "csfqw.com";
        System.Web.HttpContext.Current.Response.AppendCookie(expertcookie);
    }
    HttpContext.Current.Session.Remove("username");
    HttpContext.Current.Session.Remove("Expert");
}