下载Xml文件方法

#region 下载Xml文件方法
        //定义委托
        private delegate void DownLoadDelegate(string url, string filename);
        private DownLoadDelegate _downlaoddelegate;
        /// <summary>
        /// 文件下载
        /// </summary>
        /// <param name="url"></param>
        /// <param name="filemane"></param>
        private void download(string url, string filemane)
        {
            System.Net.WebClient wc = new System.Net.WebClient();
            wc.DownloadFile(url, filemane);
        }
        private void dlNode()
        {
            showNode(treeView1.Nodes);
        }
        private void showNode(TreeNodeCollection node)
        {
            foreach (TreeNode n in node)
            {
                if (n.GetNodeCount(false) == )
                {
                    if (n.Tag != null)
                    {
                        Thread thread = new Thread(new ThreadStart(delegate
                        {
                            this.BeginInvoke(_downlaoddelegate, n.Tag.ToString(), mf.DirData + @"\" + n.Name + ".xml");
                        }));
                        thread.IsBackground = true;
                        thread.Start();
                    }
                }
                showNode(n.Nodes);
            }

        }
        #endregion