Java 具有OneTONE关系的实体的JSON输出
我尝试生成我的实体飞行的输出,它与我的另一个实体飞机有一对一的关系,但结果为空,Eclipse开始在gson中抛出异常。在我将这个关系添加到Flight类之前,我的JSON输出没有问题。任何想法,我必须改变,使其正常工作 我的航班等级:Java 具有OneTONE关系的实体的JSON输出,java,json,eclipse,jpa,jakarta-ee,Java,Json,Eclipse,Jpa,Jakarta Ee,我尝试生成我的实体飞行的输出,它与我的另一个实体飞机有一对一的关系,但结果为空,Eclipse开始在gson中抛出异常。在我将这个关系添加到Flight类之前,我的JSON输出没有问题。任何想法,我必须改变,使其正常工作 我的航班等级: @Entity @NamedQueries({ @NamedQuery(name = "Flight.getAll", query = "SELECT f FROM Flight f"), }) @NamedQuery(name = "Flight.getByD
@Entity
@NamedQueries({ @NamedQuery(name = "Flight.getAll", query = "SELECT f FROM Flight f"), })
@NamedQuery(name = "Flight.getByDestination", query = "SELECT f FROM Flight f WHERE f.destinationFrom=:destinationFrom AND f.destinationTo=:destinationTo")
public class Flight implements Serializable {
@Transient
private static final long serialVersionUID = 1L;
public Flight() {
super();
}
public Flight(FlightDestination destinationFrom, FlightDestination destinationTo, Integer flightPrice, Date date,
Airplane airplaneDetail) {
super();
this.destinationFrom = destinationFrom;
this.destinationTo = destinationTo;
this.flightPrice = flightPrice;
this.date = date;
this.airplaneDetail = airplaneDetail;
}
public Flight(FlightDestination destinationFrom, FlightDestination destinationTo, Integer flightPrice, Date date) {
super();
this.destinationFrom = destinationFrom;
this.destinationTo = destinationTo;
this.flightPrice = flightPrice;
this.date = date;
}
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
@Enumerated(EnumType.STRING)
private FlightDestination destinationFrom;
@Enumerated(EnumType.STRING)
private FlightDestination destinationTo;
private Integer flightPrice;
@Temporal(TemporalType.DATE)
private Date date;
@OneToOne(cascade = { CascadeType.PERSIST, CascadeType.REMOVE })
@JoinColumn(name = "airplane_fk")
private Airplane airplaneDetail;
@Override
public String toString() {
return "Flight [id=" + id + ", destinationFrom=" + destinationFrom + ", destinationTo=" + destinationTo
+ ", flightPrice=" + flightPrice + ", date=" + date + ", airplaneDetail=" + airplaneDetail + "]";
}}
飞机实体:
@Entity
public class Airplane implements Serializable {
private static final long serialVersionUID = 1L;
public Airplane() {
super();
}
public Airplane(String planeModel, Integer seatingCapacity) {
super();
this.planeModel = planeModel;
this.seatingCapacity = seatingCapacity;
}
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
private String planeModel;
private Integer seatingCapacity;
@OneToOne(mappedBy = "airplaneDetail")
private Flight flight;
@Override
public String toString() {
return "Airplane [id=" + id + ", planeModel=" + planeModel + ", seatingCapacity=" + seatingCapacity
+ ", flight=" + flight + "]";
}}
我的网络服务:
@Path("/flights")
public class FlightsWebService {
@PersistenceContext(unitName = "airline")
private EntityManager em;
@EJB
private FlightService fs;
@GET
@Produces(MediaType.APPLICATION_JSON)
public List<Flight> getFlights() {
List<Flight> fList = fs.getAllFlights();
return fList;
}}
这是一个例外:
Caused by: com.owlike.genson.TransformationException: Could not serialize property 'flight' from class com.airline.models.Airplane
at com.owlike.genson.reflect.PropertyAccessor.couldNotSerialize(PropertyAccessor.java:48)
at com.owlike.genson.reflect.PropertyAccessor.serialize(PropertyAccessor.java:31)
at com.owlike.genson.reflect.BeanDescriptor.serialize(BeanDescriptor.java:87)
at com.owlike.genson.convert.BeanViewConverter.serialize(BeanViewConverter.java:92)
at com.owlike.genson.convert.NullConverter$NullConverterWrapper.serialize(NullConverter.java:51)
at com.owlike.genson.reflect.PropertyAccessor.serialize(PropertyAccessor.java:29)
at com.owlike.genson.reflect.BeanDescriptor.serialize(BeanDescriptor.java:87)
at com.owlike.genson.convert.BeanViewConverter.serialize(BeanViewConverter.java:92)
at com.owlike.genson.convert.NullConverter$NullConverterWrapper.serialize(NullConverter.java:51)
at com.owlike.genson.convert.CircularClassReferenceConverterFactory$CircularConverter.serialize(CircularClassReferenceConverterFactory.java:30)
at com.owlike.genson.reflect.PropertyAccessor.serialize(PropertyAccessor.java:29)
at com.owlike.genson.reflect.BeanDescriptor.serialize(BeanDescriptor.java:87)
at com.owlike.genson.convert.BeanViewConverter.serialize(BeanViewConverter.java:92)
at com.owlike.genson.convert.NullConverter$NullConverterWrapper.serialize(NullConverter.java:51)
at com.owlike.genson.reflect.PropertyAccessor.serialize(PropertyAccessor.java:29)
at com.owlike.genson.reflect.BeanDescriptor.serialize(BeanDescriptor.java:87)
at com.owlike.genson.convert.BeanViewConverter.serialize(BeanViewConverter.java:92)
问题是一个循环依赖项
飞行->飞机->飞行->飞机->…
。序列化程序进入一个无止境的循环。您可以在生成的输出中识别这一点
一个解决方案是忽略关系的一方,请参阅,以获取执行此操作的选项。一种方法是使用注释
@Entity
public class Airplane implements Serializable {
...
@JsonIgnore
@OneToOne(mappedBy = "airplaneDetail")
private Flight flight;
...
}
这将生成一个有飞机的航班列表,但对航班的反向引用将被忽略
[
{
"airplaneDetail":
{
"planeModel":"...",
"seatingCapacity":"..."
// NO "flight":{...}
},
"destinationFrom":{},
"destinationTo":{},
...
},
]
Maarten给我们的答案是正确的,我唯一需要改变的是,
@JsonIngore
在字段的getter方法上工作。您收到的错误是什么?预期的结果是什么?我刚刚在我的帖子中添加了这些信息。谢谢你的记忆。我已经试着用这种方法做了,但结果是一样的。
[
{
"airplaneDetail":
{
"planeModel":"...",
"seatingCapacity":"..."
// NO "flight":{...}
},
"destinationFrom":{},
"destinationTo":{},
...
},
]