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package com.student.model;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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/**
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* 学生数据仓库类，负责学生数据的存储、检索、更新和删除
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* 使用单例模式确保系统中只有一个数据仓库实例
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*/
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public class StudentRepository {
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// 使用Map存储学生数据，以ID为键
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private final Map<String, Student> students;
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// 单例实例
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private static volatile StudentRepository instance;
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/**
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* 私有构造函数，防止外部实例化
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*/
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private StudentRepository() {
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students = new HashMap<>();
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// 初始化一些示例数据
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addSampleData();
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}
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/**
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* 获取单例实例
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* @return StudentRepository实例
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*/
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public static StudentRepository getInstance() {
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if (instance == null) {
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synchronized (StudentRepository.class) {
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if (instance == null) {
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instance = new StudentRepository();
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}
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}
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}
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return instance;
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}
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/**
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* 添加示例数据
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*/
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private void addSampleData() {
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addStudent(new Student("1", "张三", 20, "计算机科学"));
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addStudent(new Student("2", "李四", 21, "软件工程"));
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addStudent(new Student("3", "王五", 19, "数据结构"));
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}
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/**
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* 添加学生
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* @param student 学生对象
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*/
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public void addStudent(Student student) {
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students.put(student.getId(), student);
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}
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/**
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* 根据ID获取学生
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* @param id 学生ID
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* @return 学生对象，如果不存在则返回null
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*/
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public Student getStudentById(String id) {
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return students.get(id);
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}
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/**
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* 获取所有学生
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* @return 学生列表
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*/
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public List<Student> getAllStudents() {
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return new ArrayList<>(students.values());
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}
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/**
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* 更新学生信息
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* @param student 更新后的学生对象
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* @return 是否更新成功
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*/
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public boolean updateStudent(Student student) {
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if (students.containsKey(student.getId())) {
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students.put(student.getId(), student);
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return true;
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}
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return false;
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}
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/**
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* 删除学生
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* @param id 学生ID
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* @return 是否删除成功
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*/
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public boolean deleteStudent(String id) {
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return students.remove(id) != null;
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}
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} |
