刷新页面时，防止滚动条上滚

  #region 刷新页面时，防止滚动条上滚
  /// <summary>
  /// Persist ScrollBar's Position After a PostBack
  /// </summary>
  private void PersistScrollPosition()
  {
   StringBuilder saveScrollPosition = new StringBuilder();
   StringBuilder setScrollPosition = new StringBuilder();
   
   RegisterHiddenField("__SCROLLPOS", "0");

   saveScrollPosition.Append("<script language='javascript'>");
   saveScrollPosition.Append("function saveScrollPosition() {");
   saveScrollPosition.Append(" document.forms[0].__SCROLLPOS.value = document.body.scrollTop;");
   saveScrollPosition.Append("}");
   saveScrollPosition.Append("document.body.onscroll=saveScrollPosition;");
   saveScrollPosition.Append("</script>");
   
   RegisterStartupScript("saveScroll", saveScrollPosition.ToString());
   
   if (Page.IsPostBack)
   {
    setScrollPosition.Append("<script language='javascript'>");
    setScrollPosition.Append("function setScrollPosition() {");
    setScrollPosition.Append(" document.body.scrollTop = " + Request["__SCROLLPOS"] + ";");
    setScrollPosition.Append("}");
    setScrollPosition.Append("document.body.onload=setScrollPosition;");
    setScrollPosition.Append("</script>");
       
    RegisterStartupScript("setScroll", setScrollPosition.ToString());
   }
  }
  #endregion