Spring Data JPA OneToMany中的级联保存

怎么在保存主表的同时将附表也保存

1 需要给附表对象设置关联的主表，然后再把附表对象设置给主表，最后save主表。

在service中

public void add(Student s){
    Set<Course> courses = s.getCourses();
    courses.forEach(c->{

        //关键
        c.setStudent(s);
    });
   studentRepositiry.save(s);

}

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

    @Column(name = "name")
    private String name;

   @ManyToOne
   @JoinColumn(name = "student_id")
    private Student student;

   //getter setter 省略

   }

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

    @Column(name = "name")
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinTable(name="student_course",joinColumns={@JoinColumn(name="student_id")},
            inverseJoinColumns={@JoinColumn(name="course_id")})
    private Set<Course> courses;

   //getter setter 省略}