用三层架构思想写学生管理系统

Student 类: 标准学生类,封装键盘录入的学生信息（id , name , age , birthday）
StudentDao 类: Dao : (Data Access Object 缩写) 用于访问存储数据的数组或集合
StudentService 类: 用来进行业务逻辑的处理（例如：判断录入的id是否存在）
StudentController 类: 和用户打交道（接收用户需求，采集用户信息，打印数据到控制台）
InfoManagerEntry 类: 程序的入口（进入到学生管理系统）

Student 类
public class Student {
private String id;
private String name;
private String age;
private String birthday;

public Student() {
}

public Student(String id, String name, String age, String birthday) {
    this.id = id;
    this.name = name;
    this.age = age;
    this.birthday = birthday;
}

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getAge() {
    return age;
}

public void setAge(String age) {
    this.age = age;
}

public String getBirthday() {
    return birthday;
}

public void setBirthday(String birthday) {
    this.birthday = birthday;
}

}

StudentController 类
public class StudentCotroller {
static StudentService studentService = new StudentService();

public void start() {
    Scanner sc = new Scanner(System.