Question

我已经创建了树视图的用户控件。我需要在页面的回发中保持他的状态。为了维护树视图的状态，我使用了会话，但是我使用了out proc会话管理，并且由于这个树视图会话对象无法序列化。有没有其他方法来维护树视图的状态。这是代码

  <asp:TreeView Height="100%" ID="MyTreeView" OnTreeNodeCollapsed="MyTreeView_TreeNodeCollapsed" OnTreeNodeExpanded="MyTreeView_TreeNodeExpanded"  />


  protected void MyTreeView_TreeNodeCollapsed(object sender, EventArgs e)
    {
        if (!IsPostBack) return;
        state = new TreeViewState("TreeViewState");
        state.SaveTreeView(MyTreeView, "TreeViewState", HttpContext.Current);
    }

    protected void MyTreeView_TreeNodeExpanded(object sender, EventArgs e)
    {
        if (!IsPostBack) return;
        state = new TreeViewState("TreeViewState");
        state.SaveTreeView(MyTreeView, "TreeViewState", HttpContext.Current);
    }

上述方法来自http://code.msdn.microsoft.com/CSASPNETMaintainTreeViewSta-c7673683

Answer 1

我的母版页上有一个TreeView，我将状态保存在cookie中，因此导航到不同的页面并不总是折叠导航树。

在母版页中，我会在卸载页面之前存储树的状态：

<script type="text/javascript" language="javascript">
        window.onbeforeunload = function () {
            try {
                // The expanded state of the treeview is available in the hidden input
                // ..._ExpandState. Store that string in a cookie so we have it on the server
                // side when the page is loaded in order to restore the state of the treeview.
                var expInfo = document.getElementById('<%=TreeView1.ClientID%>' + '_ExpandState');
                if (expInfo)
                {
                    createCookie('ToolsTVExpand', expInfo.value, 365);
                }
            }
            catch (err) {
                // Ignore the error
            }
        }
        function createCookie(name, value, days) {
            if (days) {
                var date = new Date();
                date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
                var expires = "; expires=" + date.toGMTString();
            }
            else var expires = "";
            document.cookie = name + "=" + value + expires + "; path=/";
        }
</script>

然后在后面的代码中：

protected void Page_Load(object sender, EventArgs e)
{
  ....
  // If this is the initial loading of the page, restore the navigation tree view state
  if (!IsPostBack)
      reloadTreeviewState();
}

/*
 * The Tools treeview state is stored in a cookie by the client before the user navigates
 * away from the page. It's in the form of one character per node with 'e' being expanded.
 */
public void reloadTreeviewState()
{
    try
    {
        HttpCookie cookie = Request.Cookies["ToolsTVExpand"];
        if (cookie != null && cookie.Value != null)
        {
            int currIdx = 0;
            foreach (TreeNode mainNode in TreeView1.Nodes)
            {
                currIdx = setNodeStates(mainNode, cookie.Value, currIdx);
            }
        }
    }
    catch (Exception e)
    {
        // Just keep going
    }
}
protected int setNodeStates(TreeNode node, String stateInfo, int currIdx)
{
    if (currIdx >= stateInfo.Length)
        throw new Exception("State info shorter than list of nodes.");
    Char state = stateInfo[currIdx];`enter code here`
    if (state == 'e')
    {
        node.Expand();
    }
    currIdx++;
    if (node.ChildNodes != null && node.ChildNodes.Count != 0)
    {
        foreach (TreeNode childNode in node.ChildNodes)
        {
            currIdx = setNodeStates(childNode, stateInfo, currIdx);
        }
    }

    return currIdx;
}

在asp.net中保持树视图控件中collasped / Expanded节点的状态

1 个答案: