How to detect Page Refresh

hi
i want to detect the page refresh..
i do some work in my pageLoad Event and i have no btn or other controls on my page, i want to my code in pageLoad run just one time, not any more by pressing  F5 btn of browser by usres...
any idea plz?
i find some solution like:
protected override void LoadViewState(object savedState) { object[] allStates = (object[])savedState; base.LoadViewState(allStates[0]); _refreshState = (bool)allStates[1]; _isRefresh = _refreshState == (bool)Session["__ISREFRESH"]; } protected override object SaveViewState() { Session["__ISREFRESH"] = _refreshState; object[] allStates = new object[2]; allStates[0] = base.SaveViewState(); allStates[1] = !_refreshState; return allStates; }


but because ...