在Windows操作系统中，有一个记事本（noteopad.exe）程序，用来进行文本的编辑。请编写一个程序，实现该软件的基本功能。(1)主类名字为SimpleNotepad。(2)只需要实现保存文件和打开文件功能。保存为TXT格式，并且能够对文件命名。打开文件格式为TXT格式。(In the windows operating system, there is a notepad (notepad. exe) program for text editing. Please write a program to realize the basic functions of the software. (1) The main class name is simplenotepad. (2) Only the function of saving and opening files is needed. Save to TXT format and be able to name the file. Open the file in the format of TXT.)