生成目录树结构的一个好范例，自动读取指定文件夹的内容，并遍历文件夹下的目录，最后生成TREE目录树结构。在XP下测试通过。-Generate a good example of the directory tree structure, automatically read the contents of the specified folder, and traverse the directory folder, and finally generate TREE directory tree structure. By tested under XP.