if (p.Value.ToString().Length == 1)               

                {

                    newNode = new TreeNode((string)p.Attribute("cdmc"));

                    lc_txt = (string)p.Attribute("sxbm");

                    ln_sxbm1 = int.Parse(lc_txt);

                    treeView1.Nodes[ln_sxbm1].Nodes.Add(newNode);

                    //把 cdbm 值赋给 Tag

                    newNode.Tag = p.Value;                        

                }

                //添加 TreeView 控件 2 级节点

                if (p.Value.ToString().Length == 2)               

                {

                    newNode = new TreeNode((string)p.Attribute("cdmc"));

                    lc_txt = (string)p.Attribute("sxbm");

                    ln_sxbm1 = int.Parse(lc_txt.Substring(0, 1));

                    ln_sxbm2 = int.Parse(lc_txt.Substring(1, 1));

                    treeView1.Nodes[ln_sxbm1].Nodes[ln_sxbm2].Nodes.Add(newNode);

                    newNode.Tag = p.Value;

                }

                //添加 TreeView 控件 3 级节点

                if (p.Value.ToString().Length == 3)                 

                {

                    lc_txt = (string)p.Attribute("sxbm");

                    newNode = new TreeNode((string)p.Attribute("cdmc"));

                    ln_sxbm1 = int.Parse(lc_txt.Substring(0, 1));

                    ln_sxbm2 = int.Parse(lc_txt.Substring(1, 1));

                    ln_sxbm3 = int.Parse(lc_txt.Substring(2, 1));

             treeView1.Nodes[ln_sxbm1].Nodes[ln_sxbm2].Nodes[ln_sxbm3].Nodes.Add(newNode);