Question

“考虑一个类注册。它有两组getter和setter。一组用于教授，一组用于学生。学生可以注册自己但无法获得注册数据。另一方面，教授可以注册并查看其数据和学生数据。如何通过公共方法实现这一目标。“

以下是我对上述问题的解决方案。解决方案是正确的，如果不是为什么以及什么是解决这个问题的正确解决方案。

public class Register {
private String professor;
private String student;

public String getProfessor() {
    return professor;
}

public void setProfessor(String professor) {
    this.professor = professor;
}

public String getStudent() {
    return student;
}

public void setStudent(String student) {
    this.student = student;


   }
}

public class Student extends Register {

    public Student(String student) {
        super.setStudent(student);
    }

    @Override
    public String getProfessor() {
        return null;
    }

    @Override
    public String getStudent() {
        return null;
    }

    @Override
    public void setProfessor(String professor) {
        super.setProfessor(null);
    }
}

public class Professor extends Register {

    public Professor(String student, String professor) {
        super.setStudent(student);
        super.setProfessor(professor);
    }

}

public class Main {
    public static void main(String[] args) {

        Student std1 = new Student("Rumman");
        System.out.println("Data from Student Object");
        System.out.println("Student Name = " + std1.getStudent());
        System.out.println("Professor Name = " + std1.getProfessor());

        System.out.println("--------------------------");

        Professor prof1 = new Professor("Rumman", "Sadiq");
        System.out.println("Data from Professor Object");
        System.out.println("Student Name = " + prof1.getStudent());
        System.out.println("Professor Name = " + prof1.getProfessor());


    }
}

输出：

Data from Student Object
Student Name = null
Professor Name = null
--------------------------
Data from Professor Object
Student Name = Rumman
Professor Name = Sadiq

Answer 1

当学生尝试更改某些感知数据时，创建在实际注册时保护的代理：

注册界面

public interface Register {
    String getProfessor();

    void setProfessor(String professor);

    String getStudent();

    void setStudent(String student);
}

真实注册

public class RegisterImpl implements Register {
    private String professor;
    private String student;

    @Override
    public String getProfessor() {
        return professor;
    }

    @Override
    public void setProfessor(String professor) {
        this.professor = professor;
    }

    @Override
    public String getStudent() {
        return student;
    }

    @Override
    public void setStudent(String student) {
        this.student = student;


    }
}

安全注册

public class StudentRegister implements Register {
    private final Register register;

    public StudentRegister(Register register) {
        this.register = register;
    }

    @Override
    public String getProfessor() {
        throw new SecurityException("this is not allowed for students");
    }

    @Override
    public void setProfessor(String professor) {
        throw new SecurityException("this is not allowed for students");
    }

    @Override
    public String getStudent() {
        throw new SecurityException("this is not allowed for students");
    }

    @Override
    public void setStudent(String student) {
        register.setStudent(student);
    }
}

和管理员的控制寄存器

public final class Manager {
    private final Register register;

    public Manager(Register register) {
        this.register = register;
    }

    public Register getRegister(String password) {
        if (password.equals("professor password")) {
            return register;
        } else {
            return new StudentRegister(register);
        }

    }
}

测试课

    public class Main {
        private final static Manager manager = new Manager(new RegisterImpl());

        public static void main(String[] args) {
            professorUser();
            studentUser();
        }

        public static void professorUser() {
            Register register = manager.getRegister("professor password");
            register.setProfessor("James Gosling");
            register.setStudent("Duke");
            System.out.println(register.getProfessor());
            System.out.println(register.getStudent());
        }

        public static void studentUser() {
            Register register = manager.getRegister("student password");
            register.setStudent("Duke"); // <- allowed
            // all actions below not allowed and cause exception when student try to do it
            register.setProfessor("None");
            register.getStudent();
            register.getProfessor();


         }
}

这是为某些类添加限制的正确方法吗？

1 个答案: