使用Swing组件编写一个文本编辑程序，程序启动后，多行文本输入框TextArea中显示当前目录下myText.txt文件中原有的内容，如果该文件不存在，则新建该文件。“保存”按钮功能：将多行文本输入框TextArea中的内容写入myText.txt文件中保存。“取消”按钮功能：将多行文本输入框TextArea中的内容清空。“退出”按钮功能：退出程序

-Using Swing components to write a text editing program, the program starts, multi-line text input box TextArea to display the current directory myText.txt file any original content, if the file does not exist, create the file. "Save" button functions: multi-line text input box write the contents of the TextArea myText.txt file saved. "Cancel" button functions: multi-line text input box empty the contents of the TextArea. "Exit" button functions: exit the program