MVC/StudentController.java

package com.studentmanagement.controller;

import com.studentmanagement.exception.DuplicateStudentException;
import com.studentmanagement.exception.StudentNotFoundException;
import com.studentmanagement.model.Student;
import com.studentmanagement.model.StudentDAO;
import com.studentmanagement.view.StudentView;

import java.util.List;

/**
 * 学生控制器类
 * 负责协调模型和视图之间的交互，处理业务逻辑
 */
public class StudentController {
    private StudentDAO studentDAO;
    private StudentView studentView;

    /**
     * 构造函数
     * @param studentView 学生视图对象
     */
    public StudentController(StudentView studentView) {
        this.studentDAO = StudentDAO.getInstance();
        this.studentView = studentView;
    }

    /**
     * 添加学生
     * @param student 学生对象
     */
    public void addStudent(Student student) {
        try {
            studentDAO.addStudent(student);
            studentView.displaySuccessMessage("学生添加成功: " + student.getName());
        } catch (DuplicateStudentException e) {
            studentView.displayErrorMessage("学生添加失败: " + e.getMessage());
        }
    }

    /**
     * 显示所有学生
     */
    public void displayAllStudents() {
        List<Student> students = studentDAO.getAllStudents();
        studentView.displayStudentList(students);
    }

    /**
     * 根据ID查找学生
     * @param id 学生ID
     */
    public void findStudentById(String id) {
        try {
            Student student = studentDAO.getStudentById(id);
            studentView.displayStudentDetails(student);
        } catch (StudentNotFoundException e) {
            studentView.displayErrorMessage(e.getMessage());
        }
    }

    /**
     * 更新学生信息
     * @param student 学生对象
     */
    public void updateStudent(Student student) {
        try {
            studentDAO.updateStudent(student);
            studentView.displaySuccessMessage("学生信息更新成功: " + student.getName());
        } catch (StudentNotFoundException e) {
            studentView.displayErrorMessage("学生更新失败: " + e.getMessage());
        }
    }

    /**
     * 删除学生
     * @param id 学生ID
     */
    public void deleteStudent(String id) {
        try {
            Student student = studentDAO.getStudentById(id);
            studentDAO.deleteStudent(id);
            studentView.displaySuccessMessage("学生删除成功: " + student.getName());
        } catch (StudentNotFoundException e) {
            studentView.displayErrorMessage("学生删除失败: " + e.getMessage());
        }
    }

    /**
     * 根据课程筛选学生
     * @param course 课程名称
     */
    public void filterStudentsByCourse(String course) {
        List<Student> students = studentDAO.getStudentsByCourse(course);
        if (students.isEmpty()) {
            studentView.displayErrorMessage("未找到选修课程'" + course + "'的学生");
        } else {
            studentView.displayFilteredStudents(students, "课程: " + course);
        }
    }

    /**
     * 根据成绩范围筛选学生
     * @param minGrade 最低成绩
     * @param maxGrade 最高成绩
     */
    public void filterStudentsByGradeRange(double minGrade, double maxGrade) {
        List<Student> students = studentDAO.getStudentsByGradeRange(minGrade, maxGrade);
        if (students.isEmpty()) {
            studentView.displayErrorMessage("未找到成绩在" + minGrade + "-" + maxGrade + "范围内的学生");
        } else {
            studentView.displayFilteredStudents(students, "成绩范围: " + minGrade + "-" + maxGrade);
        }
    }

    /**
     * 计算某门课程的平均成绩
     * @param course 课程名称
     */
    public void calculateAverageGradeByCourse(String course) {
        List<Student> students = studentDAO.getStudentsByCourse(course);
        if (students.isEmpty()) {
            studentView.displayErrorMessage("未找到选修课程'" + course + "'的学生");
            return;
        }

        double sum = 0.0;
        int count = 0;
        for (Student student : students) {
            Double grade = student.getCourseGrade(course);
            if (grade != null) {
                sum += grade;
                count++;
            }
        }

        if (count > 0) {
            double average = sum / count;
            studentView.displayStatistics("课程'" + course + "'的平均成绩: " + String.format("%.2f", average));
        } else {
            studentView.displayErrorMessage("无法计算课程'" + course + "'的平均成绩");
        }
    }

    /**
     * 计算所有学生的平均年龄
     */
    public void calculateAverageAge() {
        List<Student> students = studentDAO.getAllStudents();
        if (students.isEmpty()) {
            studentView.displayErrorMessage("当前没有学生记录");
            return;
        }

        int sum = 0;
        for (Student student : students) {
            sum += student.getAge();
        }

        double average = (double) sum / students.size();
        studentView.displayStatistics("学生平均年龄: " + String.format("%.2f", average));
    }
}