c# - LoadControlState 没有被解雇

Question

我在使用自定义控件(继承自用户控件)时遇到问题 - 我的 LoadControlState 没有被触发。

嗯，准确地说:它正常触发，但是当我覆盖页面的 LoadPageStateFromPersistenceMedium 和 SavePageStateToPersistenceMedium 函数时，它不再被触发。

是否有任何我应该调查的导致 LoadControlState 未被触发的典型原因？它何时被解雇是否有任何先决条件？

谢谢

Answer 1

就其值(value)而言，以下是我如何覆盖 Save/LoadPageStateFromPersistenceMedium 函数。基本上，它将 View 状态存储在用户 session 中，以使回发更快:

    // Inspired by: http://aspalliance.com/72
    const string ViewStateFieldName = "__VIEWSTATEKEY";
    const string ViewStateKeyPrefix = "ViewState_";
    const string RecentViewStateQueue = "ViewStateQueue";
    const int RecentViewStateQueueMaxLength = 5;

    protected override object LoadPageStateFromPersistenceMedium()
    {
        // The cache key for this viewstate is stored in a hidden field, so grab it
        string viewStateKey = Request.Form[ViewStateFieldName] as string;
        if (viewStateKey == null) return null;

        // Grab the viewstate data using the key to look it up
        return Session[viewStateKey];
    }

    protected override void SavePageStateToPersistenceMedium(object viewState)
    {
        // Give this viewstate a random key
        string viewStateKey = ViewStateKeyPrefix + Guid.NewGuid().ToString();

        // Store the viewstate
        Session[viewStateKey] = viewState;

        // Store the viewstate's key in a hidden field, so on postback we can grab it from the cache
        ClientScript.RegisterHiddenField(ViewStateFieldName, viewStateKey);

        // Some tidying up: keep track of the X most recent viewstates for this user, and remove old ones
        var recent = Session[RecentViewStateQueue] as Queue<string>;
        if (recent == null) Session[RecentViewStateQueue] = recent = new Queue<string>();
        recent.Enqueue(viewStateKey); // Add this new one so it'll get removed later
        while (recent.Count > RecentViewStateQueueMaxLength) // If we've got lots in the queue, remove the old ones
            Session.Remove(recent.Dequeue());
    }