MVC/StudentController.java

// 学生控制器 - Controller层
import java.util.List;
import java.util.Scanner;

public class StudentController {
    private StudentModel model;
    private StudentView view;
    private Scanner scanner;

    public StudentController(StudentModel model, StudentView view) {
        this.model = model;
        this.view = view;
        this.scanner = new Scanner(System.in);
    }

    // 启动控制器
    public void start() {
        boolean running = true;
        while (running) {
            view.displayMenu();
            String choice = scanner.nextLine();
            
            switch (choice) {
                case "1":
                    addStudent();
                    break;
                case "2":
                    deleteStudent();
                    break;
                case "3":
                    updateStudent();
                    break;
                case "4":
                    findStudent();
                    break;
                case "5":
                    displayAllStudents();
                    break;
                case "6":
                    running = false;
                    view.displayMessage("感谢使用学生管理系统！");
                    break;
                default:
                    view.displayMessage("无效的选择，请重新输入！");
            }
        }
        scanner.close();
    }

    // 添加学生
    private void addStudent() {
        System.out.print("请输入学生ID: ");
        String id = scanner.nextLine();
        System.out.print("请输入学生姓名: ");
        String name = scanner.nextLine();
        System.out.print("请输入学生年龄: ");
        String age = scanner.nextLine();
        System.out.print("请输入学生课程: ");
        String course = scanner.nextLine();

        Student student = new Student(id, name, age, course);
        if (model.addStudent(student)) {
            view.displayMessage("学生添加成功！");
        } else {
            view.displayMessage("学生ID已存在，添加失败！");
        }
    }

    // 删除学生
    private void deleteStudent() {
        System.out.print("请输入要删除的学生ID: ");
        String id = scanner.nextLine();
        if (model.deleteStudent(id)) {
            view.displayMessage("学生删除成功！");
        } else {
            view.displayMessage("未找到该学生，删除失败！");
        }
    }

    // 更新学生信息
    private void updateStudent() {
        System.out.print("请输入要修改的学生ID: ");
        String id = scanner.nextLine();
        Student existingStudent = model.findStudent(id);
        
        if (existingStudent == null) {
            view.displayMessage("未找到该学生，无法修改！");
            return;
        }

        System.out.println("当前学生信息: " + existingStudent);
        System.out.print("请输入新姓名 (留空不修改): ");
        String name = scanner.nextLine();
        System.out.print("请输入新年龄 (留空不修改): ");
        String age = scanner.nextLine();
        System.out.print("请输入新课程 (留空不修改): ");
        String course = scanner.nextLine();

        // 保留原值如果用户留空
        name = name.isEmpty() ? existingStudent.getName() : name;
        age = age.isEmpty() ? existingStudent.getAge() : age;
        course = course.isEmpty() ? existingStudent.getCourse() : course;

        Student updatedStudent = new Student(id, name, age, course);
        if (model.updateStudent(updatedStudent)) {
            view.displayMessage("学生信息更新成功！");
        }
    }

    // 查找学生
    private void findStudent() {
        System.out.print("请输入要查询的学生ID: ");
        String id = scanner.nextLine();
        Student student = model.findStudent(id);
        view.displayStudent(student);
    }

    // 显示所有学生
    private void displayAllStudents() {
        List<Student> students = model.getAllStudents();
        view.displayAllStudents(students);
    }
}