public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            Init();
        }

        private void Init()
        {
            string targetPath = "D:\\TW_DATA";
            treeView1.Nodes.Add("TW_LOG");    //添加第一个节点最为标题，其他节点添加到主节点下面
            TreeNode rootNode = treeView1.Nodes[0];
            ExtractAllFilesToNode(targetPath, rootNode);
        }

        /// <summary>
        /// 将指定路径下的所有文件添加到parentNode下
        /// </summary>
        /// <param name="parentPath">指定的路径</param>
        /// <param name="parentNode">指定的根节点</param>
        private void ExtractAllFilesToNode(string parentPath, TreeNode parentNode)
        {
            try
            {
                if (Directory.Exists(parentPath))
                {
                    string[] subDirNames = Directory.GetDirectories(parentPath);
                    string[] subFileNames = Directory.GetFiles(parentPath);

                    for (int j = 0; j < subFileNames.Length; j++)   //是文本文件就创建该新节点添加到指定的父节点
                    {

                        parentNode.Nodes.Add(Path.GetFileNameWithoutExtension(subFileNames[j]));
                        parentNode.LastNode.Tag = subFileNames[j];   //当前节点添加进去就是最后一个节点，用LastNode定位到它
                    }
                    for (int j = 0; j < subDirNames.Length; j++) //是文件夹就递归找到所有文件
                    {
                        parentNode.Nodes.Add(Path.GetFileName(subDirNames[j]));  //文件夹也要加节点
                        ExtractAllFilesToNode(subDirNames[j], parentNode.LastNode);
                    }

                }
            }
            catch (Exception)
            {

            }
        }




  

        private void treeView1_NodeMouseDoubleClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            int linesCount = 0;
            if (treeView1.SelectedNode == null)
            {
                return;
            }

            try
            {
                linesCount = Convert.ToInt32(comboBox1.Text);
                if (linesCount > 999 || linesCount < 0)
                {
                    MessageBox.Show("请输入0-999之间的整数");
                }
            }
            catch (Exception)
            {
                return;
            }


            try
            {
                if (treeView1.SelectedNode.Nodes.Count < 1)
                {
                    textBox1.Clear();
                    using (StreamReader reader = new StreamReader(treeView1.SelectedNode.Tag.ToString(), Encoding.Default))
                    {
                        for (int i = 0; i < linesCount; i++)
                        {
                            string line = reader.ReadLine();
                            if (line == null)
                            {
                                break;
                            }
                            textBox1.AppendText(line + "\r\n");
                        }
                    }
                }
            }
            catch (Exception)
            {

            }
        }
    }