一个简单的学生选课和教师对成绩的管理系统。采用面向对象的设计方法，设计好各个类、接口和方法，体现了系统的数据采用文本文件保存，保证文本文件打开查看的时候不是乱码 -A simple student enrollment and teachers on performance management systems. Object-oriented design methods, design is good in all classes, interfaces and methods, refle