CalculationService构建，有待家长相关的完善

src/main/java/com/codesdream/ase/controller/student/StudentController.java

@@ -0,0 +1,11 @@
+package com.codesdream.ase.controller.student;
+
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("student")
+public class StudentController {
+
+    public 
+}

src/main/java/com/codesdream/ase/repository/student/SCRepository.java

@@ -1,15 +0,0 @@
-package com.codesdream.ase.repository.student;
-
-import com.codesdream.ase.model.student.StudentCourse;
-import org.springframework.data.domain.Sort;
-import org.springframework.data.jpa.repository.JpaRepository;
-import org.springframework.stereotype.Repository;
-
-import java.util.List;
-
-@Repository
-public interface SCRepository extends JpaRepository<StudentCourse, Integer> {
-
-    List<StudentCourse> findByStudentId(String studentId);
-    List<StudentCourse> findByStudentId(String studentId, Sort sort);
-}

src/main/java/com/codesdream/ase/service/ActivityService.java

@@ -171,7 +171,7 @@ public class ActivityService {
      * @exception NotFoundException 对应activityId在数据库中无记录
      * @see NotFoundException
      * @param activityId
-     * @return
+     * @return 对应活动实例
      */
     private Activity getActivity(int activityId){
         Optional<Activity> optionalActivity = activityRepository.findById(activityId);

src/main/java/com/codesdream/ase/service/CalculationService.java

@@ -0,0 +1,84 @@
+package com.codesdream.ase.service;
+
+import com.codesdream.ase.exception.notfound.NotFoundException;
+import com.codesdream.ase.model.student.Course;
+import com.codesdream.ase.model.student.Student;
+import com.codesdream.ase.model.student.StudentCourse;
+import com.codesdream.ase.repository.student.CourseRepository;
+import com.codesdream.ase.repository.student.StudentCourseRepository;
+import com.codesdream.ase.repository.student.StudentRepository;
+
+import javax.annotation.Resource;
+import java.util.List;
+import java.util.Optional;
+
+public class CalculationService {
+    @Resource
+    StudentRepository studentRepository;
+
+    @Resource
+    StudentCourseRepository studentCourseRepository;
+
+    @Resource
+    CourseRepository courseRepository;
+
+    /**
+     * 用于计算指定学生的学分绩
+     * @exception NotFoundException 课程或学生id无效
+     * @param studentId 学生id
+     * @return 计算好的学分绩
+     */
+    public float calculateGPA(int studentId){
+        if(checkStudentExistence(studentId)){
+            throw new NotFoundException("No such student.");
+        }
+        List<StudentCourse> studentCourses = studentCourseRepository.findByStudentId(studentId);
+
+        float sum = 0f;
+        float credits = 0f;
+        for (StudentCourse studentCourse : studentCourses){
+
+            Optional<Course> optionalCourse = courseRepository.findById(studentCourse.getCourseId());
+            if(!optionalCourse.isPresent()){
+                throw new NotFoundException("No such course.");
+            }
+            Course course = optionalCourse.get();
+            sum += studentCourse.getScore() * course.getCredit();
+            credits += course.getCredit();
+        }
+        return sum / credits;
+    }
+
+    public float calculateAttendanceRate(int studentId, int term){
+        //Todo
+        return -1;
+    }
+
+    public float sumUpStudentAbsence (int studentId, int term){
+        //Todo
+        return -1;
+    }
+
+    public float calculateConcernRate(int parentId){
+        //Todo
+        return -1;
+    }
+
+    public float calculateGradeChange(int studentId){
+        //Todo
+        return -1;
+    }
+
+    /**
+     * 私有方法用于判断学生id是否有效
+     * @param studentId 学生id
+     * @return 是否有效
+     */
+    private boolean checkStudentExistence(int studentId){
+        Optional<Student> optionalStudent = studentRepository.findById(studentId);
+        if(!optionalStudent.isPresent()){
+            return false;
+        }
+        return true;
+    }
+}