spring boot+jpa写一个一对多的增删改查

好的，以下是 Spring Boot JPA 实现一对多增删改查的示例代码：

1. 创建实体类

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

    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Child> children = new ArrayList<>();

    // getters and setters
}

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

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "parent_id")
    private Parent parent;

    // getters and setters
}

2. 创建 Repository 接口

public interface ParentRepository extends JpaRepository<Parent, Long> {
}

3. 创建 Service 类

@Service
public class ParentService {
    @Autowired
    private ParentRepository parentRepository;

    public Parent save(Parent parent) {
        return parentRepository.save(parent);
    }

    public void delete(Long id) {
        parentRepository.deleteById(id);
    }

    public Parent findById(Long id) {
        return parentRepository.findById(id).orElse(null);
    }

    public List<Parent> findAll() {
        return parentRepository.findAll();
    }
}

4. 创建 Controller 类

@RestController
@RequestMapping("/parents")
public class ParentController {
    @Autowired
    private ParentService parentService;

    @PostMapping
    public Parent create(@RequestBody Parent parent) {
        return parentService.save(parent);
    }

    @PutMapping("/{id}")
    public Parent update(@PathVariable Long id, @RequestBody Parent parent) {
        Parent existingParent = parentService.findById(id);
        if (existingParent == null) {
            throw new RuntimeException("Parent not found");
        }
        existingParent.setName(parent.getName());
        existingParent.setChildren(parent.getChildren());
        return parentService.save(existingParent);
    }

    @DeleteMapping("/{id}")
    public void delete(@PathVariable Long id) {
        parentService.delete(id);
    }

    @GetMapping("/{id}")
    public Parent findById(@PathVariable Long id) {
        return parentService.findById(id);
    }

    @GetMapping
    public List<Parent> findAll() {
        return parentService.findAll();
    }
}

以上就是 Spring Boot JPA 实现一对多增删改查的示例代码。