Folder 1
- Item 1.1
  - Item 1.1.1
- Folder 2
  - Subfolder 2.1
    - File 2.1.1
    - File 2.1.2
  - Subfolder 2.2
    - File 2.2.1
    - File 2.2.2
- Folder 3 (closed at start)
  - File 3.1
- File 4

jQuery Treeview 简单