FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(1, "username", DateTime.Now, DateTime.Now.AddDays(365),
true, string.Format("{0}:{1}", "username", "password"), FormsAuthentication.FormsCookiePath);
//这边的 string.Format("{0}:{1}", "username", "password")，也可以改为任何值，如密码或IP
string ticString = FormsAuthentication.Encrypt(ticket);
//将加密后的票据保存为cookie
HttpCookie coo = new HttpCookie(FormsAuthentication.FormsCookieName, ticString);
//这里的IsPersistent不会自己判断，需要手工判断，但FormsAuthenticationTicket的expiration的值是有过期性的，无论cookie的Expires设置多久，只要expiration到期，即使cookie存在用户验证也将失败
if (ticket.IsPersistent)
{
coo.Expires = ticket.Expiration;
}
//使用加入了userdata的新cookie
Response.Cookies.Add(coo);
//FormsAuthentication.SetAuthCookie("username", true);//这种是快速写法，用了这种写法就可以不用自己建ticket票据，也无法使用UserData等参数了

//FormsAuthentication.SignOut//用来清除这个Cookie标记//FormsAuthentication.RedirectFromLoginPage(userID, createPersistentCookie);

// <authentication mode="Forms">
// <forms name=".MyCookie" loginUrl="Login.aspx" protection="All" timeout="60"/>
// </authentication>