利用javaApplet实现的记事本程序，类似windows自带的记事本，包括新建、退出、保存、另存为等文件操作，以及查找、替换、复制、粘贴等编辑操作-JavaApplet achieved using the Notepad program, similar built-in Notepad windows, including the new, quit, save, save for the operation and other documents, as well as find, r