抛弃sqlite转向自造轮子

先这样吧...
目前已实现基本逻辑：
- 添加一个学生
- 按名字查找学生
- 按学号查找学生
- 对学生列表进行排序
- 获取全班某课程的成绩信息
- 获取全班所有同学的总成绩信息
- 从文件中读取学生数据
希望没什么bug

src/main/java/me/lensfrex/manager/data/ManagerTool.java

@@ -1,6 +1,8 @@
 package me.lensfrex.manager.data;
 
 import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
 import java.util.Map;
 
 public class ManagerTool {
@@ -10,8 +12,108 @@ public class ManagerTool {
         this.studentData = studentData;
     }
 
+    /**
+     * 添加一个学生
+     *
+     * @param id    学生id，long格式
+     * @param name  学生姓名
+     * @param score 学生成绩，map中key为科目名称，value为相应的成绩
+     */
     public void addStudent(long id, String name, Map<String, Integer> score) {
+        Student student = new Student(id, name, score);
+        studentData.add(student);
+    }
+
+    /**
+     * 按名字查找学生
+     *
+     * @param name 学生姓名
+     * @return 学生的信息，若无该学生则返回null
+     */
+    public Student getStudent(String name) {
+        for (Student student : studentData) {
+            if (student.getName().equals(name)) {
+                return student;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * 按学号查找学生
+     *
+     * @param id 学生学号
+     * @return 学生信息，若无该学生则返回null
+     */
+    public Student getStudent(long id) {
+        for (Student student : studentData) {
+            if (student.getId() == id) {
+                return student;
+            }
+        }
+
+        return null;
+    }
+
+    public static final int SORT_COMPARE_BY_NAME = 0;
+    public static final int SORT_COMPARE_BY_ID = 1;
+    public static final int SORT_COMPARE_BY_GENERAL_SCORE = 2;
+
+    /**
+     * 对学生列表进行排序
+     *
+     * @param compareMethod 排序方式，可根据名字字典顺序（升序，0）、学生学号（升序，1）以及总成绩（降序，2）进行排序。
+     * @return 排序后的学生列表
+     */
+    public ArrayList<Student> getSortedStudentList(int compareMethod) {
+        ArrayList<Student> sortedStudentList = new ArrayList<>(studentData);
+        switch (compareMethod) {
+            case SORT_COMPARE_BY_NAME:
+                sortedStudentList.sort(Student.compareByName);
+                break;
+            case SORT_COMPARE_BY_ID:
+                sortedStudentList.sort(Student.compareById);
+                break;
+            case SORT_COMPARE_BY_GENERAL_SCORE:
+                sortedStudentList.sort(Student.compareByGeneralScore);
+                break;
+            default:
+                break;
+        }
+        return sortedStudentList;
+    }
 
+    /**
+     * 获取全班某课程的成绩信息
+     *
+     * @param subject 欲获取的科目信息
+     * @return 包含成绩信息的HashMap，key为学生姓名，value为该科成绩数据
+     */
+    public HashMap<String, Integer> getSubjectScores(String subject) {
+        HashMap<String, Integer> scores = new HashMap<>();
+        for (Student student : studentData) {
+            scores.put(student.getName(), student.getScore().get(subject));
+        }
+        return scores;
     }
 
+    /**
+     * 获取全班所有同学的总成绩信息
+     *
+     * @return 包含全班所有同学成绩的HashMap，key为姓名，value为总成绩数据
+     */
+    public HashMap<String, Integer> getStudentScores() {
+        HashMap<String, Integer> result = new HashMap<>();
+
+        int scoreSum = 0;
+        for (Student student : studentData) {
+            for (int score : student.getScore().values()) {
+                scoreSum += score;
+            }
+            result.put(student.getName(), scoreSum);
+            scoreSum = 0;
+        }
+        return result;
+    }
 }

src/main/java/me/lensfrex/manager/data/Student.java

@@ -1,10 +1,13 @@
 package me.lensfrex.manager.data;
 
+import java.io.Serializable;
+import java.util.Comparator;
 import java.util.Map;
 
-public class Student {
+public class Student implements Serializable {
     private String name;
     //private String id;
+    // 改用long是因为方便排序 ：）
     private long id;
     private Map<String, Integer> score;
 
@@ -32,9 +35,24 @@ public class Student {
         this.score = score;
     }
 
-    public Student(String name, long id, Map<String, Integer> score) {
+    public Student(long id, String name, Map<String, Integer> score) {
-        this.name = name;
         this.id = id;
+        this.name = name;
         this.score = score;
     }
+
+    public static Comparator<Student> compareByName = (s1, s2) -> s1.getName().compareTo(s2.getName());
+    public static Comparator<Student> compareById = (s1, s2) -> (int) (s1.id - s2.id);
+    public static Comparator<Student> compareByGeneralScore = (s1, s2) -> {
+        int student1GeneralScore = 0, student2GeneralScore = 0;
+        for (int score : s1.getScore().values()) {
+            student1GeneralScore += score;
+        }
+
+        for (int score : s2.getScore().values()) {
+            student2GeneralScore += score;
+        }
+
+        return student1GeneralScore - student2GeneralScore;
+    };
 }

src/main/java/me/lensfrex/manager/data/StudentManager.java

@@ -5,6 +5,7 @@ import java.util.ArrayList;
 public class StudentManager {
     private ArrayList<Student> studentData = new ArrayList<>();
 
+    public void addStudent() {
 
-
+    }
 }

src/main/java/me/lensfrex/manager/utils/DataLoader.java

@@ -0,0 +1,43 @@
+package me.lensfrex.manager.utils;
+
+import me.lensfrex.manager.data.Student;
+
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.ObjectInputStream;
+import java.util.ArrayList;
+
+/**
+ *  参考自以前的项目：
+ *  https://github.com/lensferno/dogename/blob/main/Dogename/src/main/java/me/lensferno/dogename/data/History.java
+ */
+public class DataLoader {
+    private static final String DATA_FILE = "files/students.data";
+
+    /**\
+     *  从默认路径（files/student.data）加载学生数据，若文件不存在或读取过程中发生错误，则新建一个空的ArrayList
+     * @return 加载读取的结果，若文件不存在或读取过程中发生错误，则返回一个空的ArrayList
+     */
+    public ArrayList<Student> load() {
+        File historyFile = new File(DATA_FILE);
+        try {
+            if (!historyFile.exists()) {
+                historyFile.getParentFile().mkdirs();
+                historyFile.createNewFile();
+                return new ArrayList<>();
+            }
+
+            ObjectInputStream ois = new ObjectInputStream(new FileInputStream(historyFile));
+            ois.close();
+            return (ArrayList<Student>) ois.readObject();
+        } catch (EOFException e) {
+            System.out.println("Data file is empty.");
+            return new ArrayList<>();
+        } catch (Exception e) {
+            System.out.println("Failed to load data file:" + e);
+            e.printStackTrace();
+            return new ArrayList<>();
+        }
+    }
+}