本篇是一个案例，其核心通过代码展示代码中的递归这个用法，程序的界面如下：

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" alt="" />

当点击“加载”按钮时，根据路径中的地址，加载该文件夹下所有的子文件夹和子文件，代码如下：

 private void BtnLoad_Click(object sender, EventArgs e)

         {

             string sPath = txtPath.Text.Trim();

             LoadDirAndFile(sPath, tvList.Nodes);

         }

         private void LoadDirAndFile(string sPath, TreeNodeCollection treeNodeCollection)

         {

             string strDir = sPath.Substring(sPath.LastIndexOf(@"\") + );

             TreeNode tNode = treeNodeCollection.Add(strDir);

             //加载所有目录

             string[] strDir1 = Directory.GetDirectories(sPath);

             foreach (string item in strDir1)

             {

                 //返回目录的最后一级（名称）

                 string sDir = item.Substring(item.LastIndexOf(@"\") + );

                 TreeNode tNode1 = tNode.Nodes.Add(sDir);

                 LoadDirAndFile(item, tNode1.Nodes);     //递归加载

             }

             string[] strFiles = Directory.GetFiles(sPath, "*.txt");

             foreach (string item in strFiles)

             {

                 TreeNode tNodeFile = treeNodeCollection.Add(Path.GetFileName(item));

                 tNodeFile.Tag = item;

             }

         }

         private void tvList_NodeMouseDoubleClick(object sender, TreeNodeMouseClickEventArgs e)

         {

             if (e.Node.Tag!=null)

             {

                 //文件节点

                 txtContent.Text = File.ReadAllText(e.Node.Tag.ToString(), Encoding.Default);

             }

         }

总结：

1.加载文件夹节点时，要考虑到文件夹下还有可能有子文件夹和子文件，所以要使用递归加载；

2.在实现点击文件节点，要在右边的文本框中查看文本文件全部的内容，就在递归加载文件夹和文件时，为所有的文件节点加了tag属性，后面双击节点时，只要tag属性不为空即为文件节点（读取即可），而为空的则是文件夹节点（不需要处理）。