json序列化已经有了id（java.lang.String）的POJO

Question

我序列化了两个实体，并使用spring framework 4.2.5+jacksonjson 2.7.5将其发送到客户端。我的实体如下：

@Entity
@Table(name = "entrada")
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="idEntrada")
public class EntradaTest implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@Column(name = "id_entrada", unique = true, nullable = false)
private String idEntrada;

@Column(nullable = false, length = 5)
private String codigo;

private Integer recibidos;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_pesador_bruto")
private Empleado pesadorBruto;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "dEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_pesador_tara")
private Empleado pesadorTara;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_representante_bruto")
private Empleado representanteBruto;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_representante_tara")
private Empleado representanteTara;

@ManyToOne
@JoinColumn(name = "id_oficina", nullable = false)
private Entidad oficina;
}

@Entity
@Table(name = "empleado")
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="idEmpleado", scope = Empleado.class)
class Empleadoest implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@Column(name = "id_empleado", unique = true, nullable = false)
private String idEmpleado;

@Column(nullable = false, length = 125)
private String nombre;

@OneToMany(mappedBy = "pesadorBruto")
private Set<Entrada> entradasPesadorBruto;

@OneToMany(mappedBy = "pesadorTara")
private Set<Entrada> entradasPesadorTara;

@OneToMany(mappedBy = "representanteBruto")
private Set<Entrada> entradasRepresentanteBruto;

@OneToMany(mappedBy = "representanteTara")
private Set<Entrada> entradasRepresentanteTara;
}

我的休息服务终点是

@RequestMapping(value = "/entradas/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Entrada> getEntrada(@PathVariable("id") String idEntrada) {
Entrada entrada = entradaService.get(idEntrada);
if (entrada == null) {
return new ResponseEntity<Entrada>(HttpStatus.NOT_FOUND);
}
return new ResponseEntity<Entrada>(entrada, HttpStatus.OK);
}

@RequestMapping(value = "/entradas/", method = RequestMethod.POST)
public ResponseEntity<Void> createEntrada(@RequestBody Entrada entrada, UriComponentsBuilder ucBuilder) {

entradaService.save(entrada);

HttpHeaders headers = new HttpHeaders();
headers.setLocation(ucBuilder.path("/entradas/{id}").buildAndExpand(entrada.getIdEntrada()).toUri());
return new ResponseEntity<Void>(headers, HttpStatus.CREATED);
}

我发送给客户端的序列化数据如下所示：

{
"idEntrada": "e375ecf9-dabd-4c76-8813-0679818f9590",
"codigo": "378-2",
"recibidos": 0,
"pesadorBruto": "0c23c490-a54a-495d-9447-dc6227520646",
"pesadorTara": "874dfe26-11cb-48e4-916e-bf8a83187dcb",
"representanteBruto": "5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"representanteTara": "5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"oficina": {
"idEntidad": "f3964add-3ae8-4392-bafc-cffb9643ec15",
"nombre": "O.P.C.",
},
}

但当我尝试将数据发送回服务器时，如下所示创建一个新实体

{
"idEntrada":"e375ecf9-dabd-4c76-8813-0679818f9590",
"codigo":"378-2",
"pesadorBruto":{
"idEmpleado":"0c23c490-a54a-495d-9447-dc6227520646",
"nombre":"J. CABRERA",
},
"pesadorTara":{
"idEmpleado":"874dfe26-11cb-48e4-916e-bf8a83187dcb",
"nombre":"L. A. DELGADO",
},
"representanteBruto":{
"idEmpleado":"5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"nombre":"C. MARQUEZ",
},
"representanteTara":{
"idEmpleado":"5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"nombre":"C. MARQUEZ",
},
"oficina":{
"idEntidad":"f3964add-3ae8-4392-bafc-cffb9643ec15",
"nombre":"O.P.C.",
},
}

杰克逊失败了：

Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException:
Could not read document: Already had POJO for id (java.lang.String)
[[ObjectId: key=5fb567af-805a-40dc-84bc-8f6038d8cd2f,
type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator,
scope=lt.ciader.model.Empleado]]
(through reference chain: lt.ciader.model.Entrada["representanteTara"]->lt.ciader.model.Empleado["idEmpleado"]);
nested exception is com.fasterxml.jackson.databind.JsonMappingException:
Already had POJO for id (java.lang.String)
[[ObjectId: key=5fb567af-805a-40dc-84bc-8f6038d8cd2f,
type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator,
scope=lt.ciader.model.Empleado]]
(through reference chain: lt.ciader.model.Entrada["representanteTara"]->lt.ciader.model.Empleado["idEmpleado"])

我知道Representatetara和sa representateBruto是一样的，但根据我的模型，它可以是相同的工作，甚至是pesadorTara和Pesadobruto

当我用不同的employados发送数据时，我的服务会毫无问题地获取数据并将其序列化。 我在谷歌上搜索，想找到一个解决方案，但找不到对我有帮助的答案。我回顾：

JsonMappingException: Already had POJO for id

Jackson Already had POJO for id

Spring Rest error the second time that saves Object with child properties that references the same father the second time: Already had POJO for id

https://groups.google.com/forum/#!topic/jackson-user/TSloBi1C_qk

https://github.com/edwinquaihoi/jsonidentitymanytomany/issues/1

https://github.com/FasterXML/jackson-databind/issues/266

我做错了什么。我怎样才能解决这个问题