==========2014-04-24=========winform树控件勾选方法 和获取所有选中的

http://bbs.bccn.net/thread-197567-1-1.html 

/// <summary>
        /// 已选中或取消选中树节点上的复选框时
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void depDevTreeView1_AfterCheck(object sender, TreeViewEventArgs e)
        {
            TreeNode nodeEx = (TreeNode)e.Node;
            if (nodeEx == null) return;

            if (e.Action != TreeViewAction.Unknown)
            {
                SetNodeCheckStatus(nodeEx, nodeEx.Checked);
            }
        }

	/// <summary>
        /// 设置上下级节点的状态
        /// </summary>
        /// <param name="tn">当前点击的节点</param>
        /// <param name="nodeExChecked">选中或取消的状态（true/false）</param>
        private void SetNodeCheckStatus(TreeNode tn, bool nodeExChecked)
        {
            if (tn == null) return;

            // Check children nodes

            foreach (TreeNode tnChild in tn.Nodes)
            {
                tnChild.Checked = nodeExChecked;

                SetNodeCheckStatus(tnChild, nodeExChecked);

            }

            // Set parent check status

            TreeNode tnParent = tn;

            int nNodeCount = 0;

            while (tnParent.Parent != null)
            {

                tnParent = (TreeNode)(tnParent.Parent);

                nNodeCount = 0;

                foreach (TreeNode tnTemp in tnParent.Nodes)

                    if (tnTemp.Checked == nodeExChecked)

                        nNodeCount++;

                if (nNodeCount == tnParent.Nodes.Count)

                    tnParent.Checked = nodeExChecked;

                else

                    tnParent.Checked = false;

            }
        }

 public string checknode = "";
         /// <summary>
        /// 获取所有选中的设备/通道值
        /// </summary>
        /// <param name="treeNodeCollection">节点对象集合</param>
        /// <param name="strAllCheckedDeviceOrChannel">任务详细（对应需检测的设备/通道）</param>
        private void GetAllCheckedDeviceOrChannel(TreeNodeCollection treeNodeCollection)
        {
            foreach (TreeNode tn in treeNodeCollection)
            {

                      if (tn.Checked == true) //通道
                        {
                            checknode += tn.Tag  + ",";
                        }

                if (tn.Nodes.Count > 0)
                {
                    //当存在子节点时，递归调用获取
                    GetAllCheckedDeviceOrChannel(tn.Nodes);
                }
            }
        }