ADD file via upload

StudentController.java

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+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));
+    }
+}