diff --git a/StudentDAO.java b/StudentDAO.java
deleted file mode 100644
index 9c4241b..0000000
--- a/StudentDAO.java
+++ /dev/null
@@ -1,126 +0,0 @@
-package com.studentmanagement.model;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Optional;
-
-/**
- * 学生数据访问对象，负责学生数据的CRUD操作
- * 实现了单例模式，确保整个应用只有一个数据访问实例
- */
-public class StudentDAO {
-    // 使用单例模式
-    private static StudentDAO instance;
-    private List<Student> students;
-
-    /**
-     * 私有构造函数，初始化学生列表
-     */
-    private StudentDAO() {
-        students = new ArrayList<>();
-        // 初始化一些示例数据
-        students.add(new Student(1, "张三", 20, "Java编程", 85.5));
-        students.add(new Student(2, "李四", 21, "数据结构", 90.0));
-        students.add(new Student(3, "王五", 19, "数据库原理", 88.5));
-    }
-
-    /**
-     * 获取单例实例
-     * @return StudentDAO的唯一实例
-     */
-    public static synchronized StudentDAO getInstance() {
-        if (instance == null) {
-            instance = new StudentDAO();
-        }
-        return instance;
-    }
-
-    /**
-     * 获取所有学生
-     * @return 学生列表
-     */
-    public List<Student> getAllStudents() {
-        return new ArrayList<>(students);
-    }
-
-    /**
-     * 根据ID查找学生
-     * @param id 学生ID
-     * @return 找到的学生，如不存在返回null
-     */
-    public Student getStudentById(int id) {
-        Optional<Student> student = students.stream()
-                .filter(s -> s.getId() == id)
-                .findFirst();
-        return student.orElse(null);
-    }
-
-    /**
-     * 添加学生
-     * @param student 要添加的学生对象
-     * @return 添加是否成功
-     */
-    public boolean addStudent(Student student) {
-        // 检查ID是否已存在
-        for (Student s : students) {
-            if (s.getId() == student.getId()) {
-                return false;
-            }
-        }
-        return students.add(student);
-    }
-
-    /**
-     * 更新学生信息
-     * @param student 要更新的学生对象
-     * @return 更新是否成功
-     */
-    public boolean updateStudent(Student student) {
-        for (int i = 0; i < students.size(); i++) {
-            if (students.get(i).getId() == student.getId()) {
-                students.set(i, student);
-                return true;
-            }
-        }
-        return false;
-    }
-
-    /**
-     * 删除学生
-     * @param id 要删除的学生ID
-     * @return 删除是否成功
-     */
-    public boolean deleteStudent(int id) {
-        return students.removeIf(s -> s.getId() == id);
-    }
-
-    /**
-     * 查找特定课程的学生
-     * @param course 课程名称
-     * @return 该课程的学生列表
-     */
-    public List<Student> getStudentsByCourse(String course) {
-        List<Student> result = new ArrayList<>();
-        for (Student student : students) {
-            if (student.getCourse().equalsIgnoreCase(course)) {
-                result.add(student);
-            }
-        }
-        return result;
-    }
-
-    /**
-     * 查找成绩高于指定分数的学生
-     * @param grade 最低分数
-     * @return 成绩高于指定分数的学生列表
-     */
-    public List<Student> getStudentsByGradeAbove(double grade) {
-        List<Student> result = new ArrayList<>();
-        for (Student student : students) {
-            if (student.getGrade() >= grade) {
-                result.add(student);
-            }
-        }
-        return result;
-    }
-}
\ No newline at end of file