如何LoadControl一个使用VaryByControl OutputCache的控件,指定属性的值

public override string GetVaryByCustomString(HttpContext context, string arg)
{
    if (arg == "user")
    {
        return context.User.Identity.Name;
    }
    return base.GetVaryByCustomString(context, arg);
}

[OutputCache(Duration = 60, VaryByParam = "none", VaryByCustom = "user")]
public ActionResult MyAction()
{
    // ...
}

[OutputCache(Duration = 60, VaryByParam = "none", Location = OutputCacheLocation.Downstream)]
public ActionResult MyAction()
{
    // ...
}

[OutputCache(Duration = 60, VaryByParam = "none", Location = OutputCacheLocation.ServerAndClient)]
public ActionResult MyAction()
{
    // ...
}

[OutputCache(Duration = 60, VaryByParam = "none", Location = OutputCacheLocation.Server)]
public ActionResult MyAction()
{
    // ...
}

[OutputCache(Duration = 60, VaryByParam = "none", Location = OutputCacheLocation.None)]
public ActionResult MyAction()
{
    // ...
}