TreeView状态保存

很多时候会看到,使用Treeview的时候展开这个节点,到另外一个页面的时候Treeview的状态又恢复了,下面就是解决方法咯

新建一个类

public class TreeViewState
...{
    public void SaveTreeView(TreeView treeView, string key)
    ...{
        List<bool?> list = new List<bool?>();
        SaveTreeViewExpandedState(treeView.Nodes, list);
        HttpContext.Current.Session[key + treeView.ID] = list;
    }

    private void SaveTreeViewExpandedState(TreeNodeCollection nodes, List<bool?> list)
    ...{
        foreach (TreeNode node in nodes)
        ...{
            list.Add(node.Expanded);
            if (node.ChildNodes.Count > 0)
            ...{
                SaveTreeViewExpandedState(node.ChildNodes, list);
            }
        }
    }

    private int RestoreTreeViewIndex;

    public void RestoreTreeView(TreeView treeView, string key)
    ...{
        RestoreTreeViewIndex = 0;
        RestoreTreeViewExpandedState(treeView.Nodes,
            (List<bool?>)HttpContext.Current.Session[key + treeView.ID] ?? new List<bool?>());
    }

    private void RestoreTreeViewExpandedState(TreeNodeCollection nodes, List<bool?> list)
    ...{
        foreach (TreeNode node in nodes)
        ...{
            if (RestoreTreeViewIndex >= list.Count) return;

            node.Expanded = list[RestoreTreeViewIndex++];
            if (node.ChildNodes.Count > 0)
            ...{
                RestoreTreeViewExpandedState(node.ChildNodes, list);
            }
        }
    }
}

在页面代码,TreeView的控件里事件里写

    protected void TreeViewMain_Unload(object sender, EventArgs e)
    ...{
        // save the state of all nodes.
        new TreeViewState().SaveTreeView(TreeViewMain, this.GetType().ToString());
    }