TreeView控件保存恢复结点展开状态

帮助TreeView保存和恢复结点展开状态的辅助类

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI.WebControls;

/// <summary>

/// Heros TreeView保存和恢复结点展开状态的辅助类

/// </summary>

public class TreeNodesExpandStateManager : IDisposable

{

    TreeView _tree;

    List<TreeNode> nodes = new List<TreeNode>();

    public static string SessionKey = "TreeNodesExpandState";

    public TreeNodesExpandStateManager(TreeView tree)

    {

        _tree = tree;

    }

    /// <summary>

    /// 保存当前树的展开状态

    /// </summary>

    public void SaveExpandState()

    {

        foreach (TreeNode node in this._tree.Nodes)

        {

            SearchExpandedNode(node);

        }

    }

    private void SearchExpandedNode(TreeNode node)

    {

        if (node == null)

            return;

        else

        {

            if (node.Expanded ?? false)

            {

                nodes.Add(node);

                foreach (TreeNode item in node.ChildNodes)

                {

                    SearchExpandedNode(item);

                }

            }

        }

    }

    /// <summary>

    /// 恢复当前树的展开状态

    /// </summary>

    public void RestoreExpandState()

    {

        foreach (TreeNode node in this._tree.Nodes)

        {

            SetNodeExpandState(node);

        }

    }

    /// <summary>

    /// 用于跨页操作时，恢复到指定树

    /// </summary>

    /// <param name="tree"></param>

    public void RestoreExpandStateToTree(TreeView tree)

    {

        foreach (TreeNode node in tree.Nodes)

        {

            SetNodeExpandState(node);

        }

    }

    private void SetNodeExpandState(TreeNode node)

    {

        if (node == null)

            return;

        else

        {

            if (this.nodes.Contains(node, new EqualEntity()))

            {

                node.Expand();

                foreach (TreeNode item in node.ChildNodes)

                {

                    SetNodeExpandState(item);

                }

            }

        }

    }

    /// <summary>

    /// 将指定树展开状态存入会话，一般在树的展开和合闭事件中调用

    /// </summary>

    /// <param name="tree">目标树</param>

    public static void SaveExpandStateInSession(TreeView tree, string sessionKey)

    {

        if (tree == null)

            return;

        TreeNodesExpandStateManager manager = new TreeNodesExpandStateManager(tree);

        manager.SaveExpandState();

        HttpContext.Current.Session[sessionKey] = manager;

    }

    /// <summary>

    /// 将指定树展开状态存入默认会话，一般在树的展开和合闭事件中调用

    /// </summary>

    /// <param name="tree">目标树</param>

    public static void SaveExpandStateInSession(TreeView tree)

    {

        SaveExpandStateInSession(tree, SessionKey);

    }

    /// <summary>

    /// 将Session中的结点展开状态恢复到指定树，在树结点添加结束后调用

    /// </summary>

    /// <param name="tree">目标树</param>

    public static void RestoreExpandStateToTreeFromSession(TreeView tree, string sessionKey)

    {

        if (HttpContext.Current.Session[sessionKey] == null || tree == null)

            return;

        TreeNodesExpandStateManager manager = HttpContext.Current.Session[sessionKey] as TreeNodesExpandStateManager;

        manager.RestoreExpandStateToTree(tree);

    }

    /// <summary>

    /// 将默认Session中的结点展开状态恢复到指定树，在树结点添加结束后调用

    /// </summary>

    /// <param name="tree">目标树</param>

    public static void RestoreExpandStateToTreeFromSession(TreeView tree)

    {

        RestoreExpandStateToTreeFromSession(tree, SessionKey);

    }

    #region IDisposable 成员

    public void Dispose()

    {

        this.nodes.Clear();

        this.nodes = null;

        this._tree.Dispose();

    }

    #endregion

     ~TreeNodesExpandStateManager()

    {

        this.Dispose();

    }

     public class EqualEntity : IEqualityComparer<TreeNode>

     {

         #region IEqualityComparer<TreeNode> 成员

         public bool Equals(TreeNode x, TreeNode y)

         {

             if (x == null || y == null)

                 return false;

             return x.Value.Equals(y.Value);

         }

         public int GetHashCode(TreeNode obj)

         {

             return obj.GetHashCode();

         }

         #endregion

     }

}