**1. 級操操作** 級操操作是指：操作對象A的同時，也操作該對象關聯的其他對象。 ```java //@OneToOne、@OneToMany、@ManyToOne、@ManyToMany 都有一個屬性 cascade 來控制級聯操作 public @interface OneToMany { //配置級聯操作 //CascadeType.MERGE 級聯更新 //CascadeType.PERSIST 級聯保存 //CascadeType.REFRESH 級聯刷新 //CascadeType.REMOVE 級聯刪除 //CascadeType.ALL 所有級聯操作 CascadeType[] cascade() default {}; } ``` <br/> **2. 使用級聯操作** （1）建立實體類之間的關系。 ```java public class Mother { @OneToMany(mappedBy = "mother", fetch = FetchType.EAGER, cascade = CascadeType.ALL) private List<Children> childrenList; } ``` ```java public class Children { @ManyToOne(targetEntity = Mother.class, cascade = CascadeType.ALL) @JoinColumn(name = "mother_id", referencedColumnName = "id") private Mother mother; } ``` （2）級聯操作。 ```java /************************** Mother -> Children **************************/ /** * 級聯保存/更新。 * 保存/更新 Mother 的同時，也保存/更新 Children 表。 */ @Test public void cascadeSave() { Mother mother = Mother.builder().name("張母").build(); List<Children> childrenList = new ArrayList<>(1); Children children01 = Children.builder().name("張三").mother(mother).build(); Children children02 = Children.builder().name("張四").mother(mother).build(); childrenList.add(children01); childrenList.add(children02); mother.setChildrenList(childrenList); Mother mother1 = motherRepository.save(mother); System.out.println(mother1.getId()); } /** * 級聯刪除。 * 刪除 Mother 的同時，也刪除 Children 表。 */ @Test public void cascadeDelete() { Mother mother = Mother.builder().id(2).build(); List<Children> childrenList = new ArrayList<>(1); Children children01 = Children.builder().id(3).build(); Children children02 = Children.builder().id(4).build(); childrenList.add(children01); childrenList.add(children02); mother.setChildrenList(childrenList); motherRepository.delete(mother); } ``` ```java /************************** Children -> Mother **************************/ /** * 級聯保存/更新。 * 保存/更新 Children 的同時，也保存/更新 Mother 表。 */ @Test public void cascadeSave() { Mother mother = Mother.builder().name("王母").build(); List<Children> childrenList = new ArrayList<>(1); Children children = Children.builder().name("王三").mother(mother).build(); childrenList.add(children); mother.setChildrenList(childrenList); Children children1 = childrenRepository.save(children); System.out.println(children1.getId()); } ```