基于指定文件的班级信息管理,就是给定一个ClassHR.Info文件,从该文件里选择性的读取相关信息，在此基础上再进行增加、删除、修改、查询学生信息的操作-Based on the specified file class information management, is given a ClassHR.Info documents, documents from the selective readings of the relevant information, on this basis further to add, delete, modify, query information on the operation of student