Question

我对Hibernate-Spring MVC有几个问题。这是我从控制器到数据库实体的调用示例：

控制器

@Override
    @RequestMapping(value = { "/cars/{idFleet}"}, method = RequestMethod.GET)
    public @ResponseBody Response<List<Car>> getCars(@PathVariable int idFleet) throws QueryException{  
        return fleetAndCarService.findCarsByIdFleet(idFleet);
    }

服务

    @Override
//  @Transactional
    public Response<List<Car>> findCarsByIdFleet(int idFleet) throws QueryException {
        try{
            return new Response<List<Car>>(HttpStatus.OK.value(),databaseFleetsAndCarsServices.findCarsByIdFleet(idFleet));
        } catch (Exception e) {
            throw new QueryException(e);
        }
    }

数据库服务

@Override
    public List<Car> findCarsByIdFleet(int idFleet) {
        return carServices.findByFleetIdFleet(idFleet);
    }

带有命名查询的汽车服务

@Override
@Transactional
public List<Car> findByFleetIdFleet(int idFleet) {
    return carRepository.findByFleetIdFleet(idFleet);
}

汽车库

public interface CarRepository extends JpaRepository<Car, Integer> {

    //Query method of spring, I put findBy and then the key of research 
    List<Car> findByFleetIdFleet(int idFleet);

}

汽车实体

@Entity

@Table（name =＆＃34; car＆＃34;，catalog =＆＃34; ATS＆＃34;） public class Car实现了java.io.Serializable {

/**
 * 
 */
private static final long serialVersionUID = 1L;
private Integer idCar;
private CarType carType;
private Fleet fleet;
private String id;
private int initialKm;
private String carChassis;
private String note;
private Set<Acquisition> acquisitions = new HashSet<Acquisition>(0);

public Car() {
}

public Car(CarType carType, Fleet fleet, int initialKm, String carChassis) {
    this.carType = carType;
    this.fleet = fleet;
    this.initialKm = initialKm;
    this.carChassis = carChassis;
}

public Car(CarType carType, Fleet fleet, String id, int initialKm, String carChassis, String note,
        Set<Acquisition> acquisitions) {
    this.carType = carType;
    this.fleet = fleet;
    this.id = id;
    this.initialKm = initialKm;
    this.carChassis = carChassis;
    this.note = note;
    this.acquisitions = acquisitions;
}

@Id
@GeneratedValue(strategy = IDENTITY)

@Column(name = "id_car", unique = true, nullable = false)
public Integer getIdCar() {
    return this.idCar;
}

public void setIdCar(Integer idCar) {
    this.idCar = idCar;
}

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "id_carType", nullable = false)
public CarType getCarType() {
    return this.carType;
}

public void setCarType(CarType carType) {
    this.carType = carType;
}

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "id_fleet", nullable = false)
public Fleet getFleet() {
    return this.fleet;
}

public void setFleet(Fleet fleet) {
    this.fleet = fleet;
}

@Column(name = "id", length = 5)
public String getId() {
    return this.id;
}

public void setId(String id) {
    this.id = id;
}

@Column(name = "initialKm", nullable = false)
public int getInitialKm() {
    return this.initialKm;
}

public void setInitialKm(int initialKm) {
    this.initialKm = initialKm;
}

@Column(name = "carChassis", nullable = false, length = 20)
public String getCarChassis() {
    return this.carChassis;
}

public void setCarChassis(String carChassis) {
    this.carChassis = carChassis;
}

@Column(name = "note", length = 100)
public String getNote() {
    return this.note;
}

public void setNote(String note) {
    this.note = note;
}

@OneToMany(fetch = FetchType.LAZY, mappedBy = "car")
public Set<Acquisition> getAcquisitions() {
    return this.acquisitions;
}

public void setAcquisitions(Set<Acquisition> acquisitions) {
    this.acquisitions = acquisitions;
    }
}

汽车类型（通过外键链接，一对多关系）

/**
 * CarType generated by hbm2java
 */
@Entity
@Table(name = "carType", catalog = "ATS")
public class CarType implements java.io.Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private String idCarType;
    private String note;
    private Set<Car> cars = new HashSet<Car>(0);

    public CarType() {
    }

    public CarType(String idCarType) {
        this.idCarType = idCarType;
    }

    public CarType(String idCarType, String note, Set<Car> cars) {
        this.idCarType = idCarType;
        this.note = note;
        this.cars = cars;
    }

    @Id

    @Column(name = "id_carType", unique = true, nullable = false, length = 5)
    public String getIdCarType() {
        return this.idCarType;
    }

    public void setIdCarType(String idCarType) {
        this.idCarType = idCarType;
    }

    @Column(name = "note", length = 100)
    public String getNote() {
        return this.note;
    }

    public void setNote(String note) {
        this.note = note;
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "carType")
    public Set<Car> getCars() {
        return this.cars;
    }

    public void setCars(Set<Car> cars) {
        this.cars = cars;
    }

}

车队实体

@Entity
@Table(name = "fleet", catalog = "ATS")
public class Fleet implements java.io.Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private Integer idFleet;
    private Ecu ecu;
    private String application;
    private String cubic;
    private int power;
    private String euroClass;
    private String engineType;
    private String traction;
    private String transmission;
    private String note;
    private Set<Car> cars = new HashSet<Car>(0);

收购实体

@Entity
@Table(name = "acquisition", catalog = "ATS")
public class Acquisition implements java.io.Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private Integer idAcquisition;
    private Car car;
    private DpfWeighting dpfWeighting;
    private MissionProfile missionProfile;
    private OilSample oilSample;
    private Shift shift;
    private SwVersion swVersion;
    private Date date;
    private float sessionDuration;
    private int beginKm;
    private int endKm;
    private String driverName;
    private String dataset;
    private String drChannelsConf;
    private String excelRow;
    private Set<Rdi> rdis = new HashSet<Rdi>(0);
    private Set<SelfLearning> selfLearnings = new HashSet<SelfLearning>(0);
    private Set<Iupr> iuprs = new HashSet<Iupr>(0);

我和maven一起使用 4.2.1.RELEASE 4.3.11.Final

当我拨打我的控制器时，我收到一个例外：

com.fasterxml.jackson.databind.JsonMappingException：没有序列化程序上课时发现 org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer而且没有发现创建BeanSerializer的属性（以避免异常，禁用SerializationFeature.FAIL_ON_EMPTY_BEANS））（通过引用链： com.model.Response [＆＃34;主体＆＃34;] - ＆GT; java.util.ArrayList中[0] - ＆GT; com.domain.Car [＆＃34; carType＆＃34;] - ＆GT; com.domain .CarType _ _ $$ jvst615_e [＆＃34;处理＆＃34;]）

我想了解是否必须从实体中删除set变量，如何在映射时解决此异常。谢谢目前我在每个实体上使用@JsonIgnoreProperties（{＆＃34; hibernateLazyInitializer＆＃34;，＆＃34; handler＆＃34;}），但这是正确的吗？此外我还有cicle循环到实体查询中（是否有可能hibernate工具错误写入所有实体或我已经选择了错误的生成实体的方式？）

当我使用像

这样的存储库方法时

@Override
@Transactional
public List<Fleet> getFleets() {
    return fleetRepository.findAll();
}

没问题，效果很好

更新：我在@JsonManagedReference变量上添加了@OneToMany，在@JsonBackReference变量上添加了@ManyToOne它似乎有效，但现在在车里我只能看到收购而不是Fleet和CarType（所以有使用JsonBackReference进行注释而不是查询我收到所有对象但是carType和Fleet都是null，我需要相反，所以我需要fleet和carType，而不是获取这是我找到它的链接 Infinite Recursion with Jackson JSON and Hibernate JPA issue

Answer 1

尝试向@ManyToOne(fetch = FetchType.EAGER)实体添加Car - 属性carType（或方法getCarType - 取决于您使用的内容）。对于EAGER fetch - Car实体应该具有实体对象而不是代理对象。

从应用程序返回实体不是一个好习惯，因为您无法控制将返回哪些关系和数据。而不是你应该返回VO（值对象）。使用VO是安全的，您可以控制从应用程序返回的内容。对于从entites到VO对象（包括关系）的mappig，您可以使用一些映射器，例如Orika。

杰克逊和Hibernate异常与映射

1 个答案: