Question

我正在使用Hibernate将我的实体保存到数据库。举个简单的例子，我有两个实体：

汽车：

@Entity
@Table(name = "car")
public class Car implements Serializable {
    @Id
    @GeneratedValue
    private long id;
    private String name;
    @OneToMany(cascade = CascadeType.PERSIST)
    private List<Wheel> wheelList;

    public Car() {
    }

    public Car(String name, List<Wheel> wheelList) {
        this.name = name;
        this.wheelList = wheelList;
    }

和Wheel：

@Entity
@Table(name = "wheel")
public class Wheel implements Serializable {
    @Id
    @GeneratedValue
    private long id;
    private int size;
    @ManyToOne(cascade = CascadeType.PERSIST)
    private Car car;

    public Wheel() {
    }

    public Wheel(int size, Car car) {
        this.size = size;
        this.car = car;
    }

我正在使用Spring Framework（MVC）创建REST客户端，我从中返回JSON。现在：我创建了简单的@Repository和@Service。

我想尝试保存工作，所以我用轮子列表等创建了简单的Car对象然后，在@Service层我保留了它并将car对象返回到控制器。

最后，当我从控制器运行url时，我收到了巨大的json，因为每个Car对象都有轮子列表，然后，每个轮子都有它的车，它还有列表，列表中有车轮和车轮所以..这就是为什么我的JSON如此之大。

{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":{"id":1,"name":"SomeName","wheelList":[{"id":1,"size":1,"car":...........

我做错了什么？我该如何解决这个问题？

如果你需要它的其余代码:(仅用于测试，我知道这里没有很好的编码风格）存储库：

@Repository
public class TestImpl {
    @PersistenceContext
    private EntityManager entityManager;

    public Car saveCar(Car car){
        entityManager.persist(car);
        return car;
    }
}

服务

@Service
@Transactional
public class TestService {
    @Autowired
    private TestImpl test;

    public Car save(){
        Car car = new Car();
        car.setName("SomeName");
        List<Wheel> list = new ArrayList<Wheel>();
        list.add(new Wheel(1, car));
        car.setWheelList(list);
        test.saveCar(car);
        return car;
    }
}

控制器：

@Controller
public class TestController {
    @Autowired
    private TestService testService;

    @RequestMapping(value = "/los")
    @ResponseBody
    public Car los(){
        return testService.save();
    }
}

Answer 1

您可以将@JsonIgnore注释添加到wheelList对象中的Car字段或car对象中的Wheel字段。这将阻止JSON序列化程序在结果文档中显示这些字段，并以递归方式包含字段。

使用Hibernate保存和返回实体时使用巨大的JSON

1 个答案: