mvc分层开发实现简易学生管理系统，实现用户的登录注册，学生的增删改查，页面简单，写出完整代码

好的，我可以提供一个基于Java的MVC分层开发实现简易学生管理系统的示例代码，包括用户的登录注册和学生的增删改查功能。请注意，这只是一个简单的示例，实际项目中需要更完整的代码和更多的功能。

1. 创建MVC的三个层次（Model、View和Controller）：

Student.java（Model）

public class Student {
    private int id;
    private String name;
    private int age;
    private String gender;
    private String major;

    public Student(int id, String name, int age, String gender, String major) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.major = major;
    }

    // Getters and setters
    // ...
}

StudentDAO.java（Model）

public class StudentDAO {
    private List<Student> students = new ArrayList<Student>();

    public void addStudent(Student student) {
        students.add(student);
    }

    public void deleteStudent(int id) {
        for (Student student : students) {
            if (student.getId() == id) {
                students.remove(student);
                break;
            }
        }
    }

    public void updateStudent(Student student) {
        for (Student s : students) {
            if (s.getId() == student.getId()) {
                s.setName(student.getName());
                s.setAge(student.getAge());
                s.setGender(student.getGender());
                s.setMajor(student.getMajor());
                break;
            }
        }
    }

    public Student getStudentById(int id) {
        for (Student student : students) {
            if (student.getId() == id) {
                return student;
            }
        }
        return null;
    }

    public List<Student> getAllStudents() {
        return students;
    }
}

LoginView.java（View）

public class LoginView {
    private Scanner scanner;

    public LoginView() {
        scanner = new Scanner(System.in);
    }

    public String getUsername() {
        System.out.print("Enter username: ");
        return scanner.nextLine();
    }

    public String getPassword() {
        System.out.print("Enter password: ");
        return scanner.nextLine();
    }

    public void showLoginSuccess() {
        System.out.println("Login success!");
    }

    public void showLoginFail() {
        System.out.println("Login fail!");
    }

    public void showRegisterSuccess() {
        System.out.println("Register success!");
    }

    public void showRegisterFail() {
        System.out.println("Register fail!");
    }
}

StudentView.java（View）

public class StudentView {
    private Scanner scanner;

    public StudentView() {
        scanner = new Scanner(System.in);
    }

    public Student getStudentInfo() {
        System.out.print("Enter student id: ");
        int id = scanner.nextInt();
        scanner.nextLine();
        System.out.print("Enter student name: ");
        String name = scanner.nextLine();
        System.out.print("Enter student age: ");
        int age = scanner.nextInt();
        scanner.nextLine();
        System.out.print("Enter student gender: ");
        String gender = scanner.nextLine();
        System.out.print("Enter student major: ");
        String major = scanner.nextLine();
        return new Student(id, name, age, gender, major);
    }

    public void showAllStudents(List<Student> students) {
        System.out.println("All students:");
        for (Student student : students) {
            System.out.println(student.getId() + " " + student.getName() + " " + student.getAge() + " " + student.getGender() + " " + student.getMajor());
        }
    }

    public void showStudent(Student student) {
        System.out.println("Student info:");
        System.out.println(student.getId() + " " + student.getName() + " " + student.getAge() + " " + student.getGender() + " " + student.getMajor());
    }

    public void showAddSuccess() {
        System.out.println("Add student success!");
    }

    public void showAddFail() {
        System.out.println("Add student fail!");
    }

    public void showDeleteSuccess() {
        System.out.println("Delete student success!");
    }

    public void showDeleteFail() {
        System.out.println("Delete student fail!");
    }

    public void showUpdateSuccess() {
        System.out.println("Update student success!");
    }

    public void showUpdateFail() {
        System.out.println("Update student fail!");
    }
}

LoginController.java（Controller）

public class LoginController {
    private LoginView loginView;
    private UserDAO userDAO;

    public LoginController(LoginView loginView, UserDAO userDAO) {
        this.loginView = loginView;
        this.userDAO = userDAO;
    }

    public void login() {
        String username = loginView.getUsername();
        String password = loginView.getPassword();
        if (userDAO.checkUser(username, password)) {
            loginView.showLoginSuccess();
        } else {
            loginView.showLoginFail();
        }
    }

    public void register() {
        String username = loginView.getUsername();
        String password = loginView.getPassword();
        if (userDAO.addUser(username, password)) {
            loginView.showRegisterSuccess();
        } else {
            loginView.showRegisterFail();
        }
    }
}

StudentController.java（Controller）

public class StudentController {
    private StudentView studentView;
    private StudentDAO studentDAO;

    public StudentController(StudentView studentView, StudentDAO studentDAO) {
        this.studentView = studentView;
        this.studentDAO = studentDAO;
    }

    public void addStudent() {
        Student student = studentView.getStudentInfo();
        if (studentDAO.addStudent(student)) {
            studentView.showAddSuccess();
        } else {
            studentView.showAddFail();
        }
    }

    public void deleteStudent() {
        System.out.print("Enter student id: ");
        int id = studentView.scanner.nextInt();
        studentView.scanner.nextLine();
        if (studentDAO.deleteStudent(id)) {
            studentView.showDeleteSuccess();
        } else {
            studentView.showDeleteFail();
        }
    }

    public void updateStudent() {
        Student student = studentView.getStudentInfo();
        if (studentDAO.updateStudent(student)) {
            studentView.showUpdateSuccess();
        } else {
            studentView.showUpdateFail();
        }
    }

    public void getStudentById() {
        System.out.print("Enter student id: ");
        int id = studentView.scanner.nextInt();
        studentView.scanner.nextLine();
        Student student = studentDAO.getStudentById(id);
        if (student != null) {
            studentView.showStudent(student);
        } else {
            System.out.println("Student not found!");
        }
    }

    public void getAllStudents() {
        List<Student> students = studentDAO.getAllStudents();
        studentView.showAllStudents(students);
    }
}

2. 创建UserDAO.java（Model），用于处理用户登录和注册：

public class UserDAO {
    private Map<String, String> users = new HashMap<String, String>();

    public UserDAO() {
        users.put("admin", "admin");
    }

    public boolean checkUser(String username, String password) {
        String pw = users.get(username);
        return pw != null && pw.equals(password);
    }

    public boolean addUser(String username, String password) {
        if (users.containsKey(username)) {
            return false;
        } else {
            users.put(username, password);
            return true;
        }
    }
}

3. 创建Main.java作为程序入口：

public class Main {
    public static void main(String[] args) {
        LoginView loginView = new LoginView();
        UserDAO userDAO = new UserDAO();
        LoginController loginController = new LoginController(loginView, userDAO);

        StudentView studentView = new StudentView();
        StudentDAO studentDAO = new StudentDAO();
        StudentController studentController = new StudentController(studentView, studentDAO);

        Scanner scanner = new Scanner(System.in);
        int choice;
        do {
            System.out.println("1. Login");
            System.out.println("2. Register");
            System.out.println("0. Exit");
            System.out.print("Enter your choice: ");
            choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 1:
                    loginController.login();
                    if (userDAO.checkUser("admin", "admin")) {
                        int choice2;
                        do {
                            System.out.println("1. Add student");
                            System.out.println("2. Delete student");
                            System.out.println("3. Update student");
                            System.out.println("4. Get student by id");
                            System.out.println("5. Get all students");
                            System.out.println("0. Logout");
                            System.out.print("Enter your choice: ");
                            choice2 = scanner.nextInt();
                            scanner.nextLine();
                            switch (choice2) {
                                case 1:
                                    studentController.addStudent();
                                    break;
                                case 2:
                                    studentController.deleteStudent();
                                    break;
                                case 3:
                                    studentController.updateStudent();
                                    break;
                                case 4:
                                    studentController.getStudentById();
                                    break;
                                case 5:
                                    studentController.getAllStudents();
                                    break;
                                case 0:
                                    break;
                                default:
                                    System.out.println("Invalid choice!");
                                    break;
                            }
                        } while (choice2 != 0);
                    }
                    break;
                case 2:
                    loginController.register();
                    break;
                case 0:
                    break;
                default:
                    System.out.println("Invalid choice!");
                    break;
            }
        } while (choice != 0);
    }
}