/// <summary>
/// 在SaveViewState之前，将ViewState中所有IStateManager类型项转换为可序列化的ViewSateItemInternal类型项
/// </summary>
/// <param name="viewState">ViewState</param>
/// <remarks>在SaveViewState之前调用</remarks>
/// <example>
/// <![CDATA[
///protected override object SaveViewState()
///{
/// WebControlUtility.PreSaveViewState(ViewState);
/// object o = base.SaveViewState();
/// WebControlUtility.AfterSavedViewState(ViewState);
/// return o;
///}
/// ]]>
/// </example>
internal static void PreSaveViewState(this StateBag viewState)
{
foreach (string key in viewState.Keys)
{
IStateManager o = viewState[key] as IStateManager;
if (o != null)
{
viewState[key] = new ViewSateItemInternal(o);
}
}
}
/// <summary>
/// 在LoadViewState之后从缓存中恢复将ViewState中ViewSateItemInternal类型项恢复成IStateManager类型项
/// </summary>
/// <param name="viewState">ViewState</param>
/// <param name="backState">PreLoadViewState产生缓存的项</param>
/// <remarks>在LoadViewState之后调用</remarks>
/// <example>
/// <![CDATA[
///protected override void LoadViewState(object savedState)
///{
/// StateBag backState = WebControlUtility.PreLoadViewState(ViewState);
/// base.LoadViewState(savedState);
/// WebControlUtility.AfterLoadViewState(ViewState, backState);
///}
/// ]]>
/// </example>
internal static void AfterLoadViewState(this StateBag viewState, StateBag backState)
{
foreach (string key in viewState.Keys)
{
ViewSateItemInternal vTemp = viewState[key] as ViewSateItemInternal;
if (vTemp != null)
{
if (backState[key] != null)
{
viewState[key] = backState[key];
((IStateManager)viewState[key]).LoadViewState(vTemp.State);
}
else
{
viewState[key] = ((ViewSateItemInternal)viewState[key]).GetObject();
}
}
}
}