spring data jpa中的连接表

@Entity
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    @ManyToMany
    @JoinTable(
        name = "student_course",
        joinColumns = @JoinColumn(name = "student_id"),
        inverseJoinColumns = @JoinColumn(name = "course_id")
    )
    private Set<Course> courses = new HashSet<>();

    // getters and setters
}

@Entity
public class Course {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String title;

    @ManyToMany(mappedBy = "courses")
    private Set<Student> students = new HashSet<>();

    // getters and setters
}

@Entity
public class StudentCourse {
    @EmbeddedId
    private StudentCourseId id;

    @ManyToOne(fetch = FetchType.LAZY)
    @MapsId("studentId")
    private Student student;

    @ManyToOne(fetch = FetchType.LAZY)
    @MapsId("courseId")
    private Course course;

    private int grade;

    // getters and setters
}

@Embeddable
public class StudentCourseId implements Serializable {
    private Long studentId;
    private Long courseId;

    // getters and setters
}