我已经看到了一些关于这个主题的问题，但我无法将其应用到我的案例中，因为我尝试应用它们，但错误仍然存​​在。 所以我来揭露我的情况。

我读了一些关于它的评论，并说如果我在 Entidade 类中更改我的列 idEntidade 的名称，我就可以成功。但是我不能改变数据库。

我试图将 scope= Distritos.class 放入我的 @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idDistrito") 但它不起作用.

我需要帮助。

我正在尝试使用带有 Angular 的 spring MVC 将数据保存在我的数据库中。当我点击保存数据时，我得到了这个错误

2017-09-29 13:28:02.126  WARN 2716 --- [nio-8080-exec-2] .w.s.m.s.DefaultHandlerExceptionResolver : Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Already had POJO for id (java.lang.Long) [[ObjectId: key=1, type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator, scope=java.lang.Object]]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Already had POJO for id (java.lang.Long) [[ObjectId: key=1, type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator, scope=java.lang.Object]] (through reference chain: digifred.global.model.Distritos["idEntidade"]->digifred.global.model.Entidades["idEntidade"])
2017-09-29 13:28:02.126  WARN 2716 --- [nio-8080-exec-2] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved exception caused by Handler execution: org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Already had POJO for id (java.lang.Long) [[ObjectId: key=1, type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator, scope=java.lang.Object]]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Already had POJO for id (java.lang.Long) [[ObjectId: key=1, type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator, scope=java.lang.Object]] (through reference chain: digifred.global.model.Distritos["idEntidade"]->digifred.global.model.Entidades["idEntidade"])
2017-09-29 13:46:14.096  INFO 2716 --- [      Thread-46] ationConfigEmbeddedWebApplicationContext : Closing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@53b2ae5: startup date [Fri Sep 29 13:23:36 BRT 2017]; root of context hierarchy

我有这些课

@Entity
@Table(name = "distritos", schema="glb")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Distritos.findAll", query = "SELECT d FROM Distritos d"),
    @NamedQuery(name = "Distritos.findByIdDistrito", query = "SELECT d FROM Distritos d WHERE d.idDistrito = :idDistrito"),
    @NamedQuery(name = "Distritos.findByNome", query = "SELECT d FROM Distritos d WHERE d.nome = :nome"),
    @NamedQuery(name = "Distritos.findByCodigoDne", query = "SELECT d FROM Distritos d WHERE d.codigoDne = :codigoDne"),
    @NamedQuery(name = "Distritos.findByFlagAtivo", query = "SELECT d FROM Distritos d WHERE d.flagAtivo = :flagAtivo")})




@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idDistrito")        
public class Distritos implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id_distrito")
    private Long idDistrito;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 70)
    @Column(name = "nome")
    private String nome;
    @Size(max = 8)
    @Column(name = "codigo_dne")
    private String codigoDne;
    @Column(name = "flag_ativo")
    private Integer flagAtivo;
    @JoinColumn()
    @ManyToOne
    private Entidades idEntidade;
    @JoinColumn()
    @ManyToOne(optional = false)
    private Municipios idMunicipio;
    @JoinColumn()
    @ManyToOne(optional = false)
    private Ufs idUf;

  gets and sets .. 
}

类(Class)斗争

@Entity
@Table(name = "entidades", schema="glb")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "Entidades.findAll", query = "SELECT e FROM Entidades e"),
    @NamedQuery(name = "Entidades.findByIdEntidade", query = "SELECT e FROM Entidades e WHERE e.idEntidade = :idEntidade"),
    @NamedQuery(name = "Entidades.findByBairro", query = "SELECT e FROM Entidades e WHERE e.bairro = :bairro"),
    @NamedQuery(name = "Entidades.findByBrasao", query = "SELECT e FROM Entidades e WHERE e.brasao = :brasao"),
    @NamedQuery(name = "Entidades.findByCnpj", query = "SELECT e FROM Entidades e WHERE e.cnpj = :cnpj"),
    @NamedQuery(name = "Entidades.findByComplemento", query = "SELECT e FROM Entidades e WHERE e.complemento = :complemento"),
    @NamedQuery(name = "Entidades.findByEmail", query = "SELECT e FROM Entidades e WHERE e.email = :email"),
    @NamedQuery(name = "Entidades.findByLogradouro", query = "SELECT e FROM Entidades e WHERE e.logradouro = :logradouro"),
    @NamedQuery(name = "Entidades.findByNome", query = "SELECT e FROM Entidades e WHERE e.nome = :nome"),
    @NamedQuery(name = "Entidades.findByNumero", query = "SELECT e FROM Entidades e WHERE e.numero = :numero"),
    @NamedQuery(name = "Entidades.findBySigla", query = "SELECT e FROM Entidades e WHERE e.sigla = :sigla"),
    @NamedQuery(name = "Entidades.findByTelefone", query = "SELECT e FROM Entidades e WHERE e.telefone = :telefone")})


@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEntidade")  
public class Entidades implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    private Long idEntidade;
    @Size(max = 50)
    private String bairro;
    private BigInteger brasao;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 14)
    private String cnpj;
    @Size(max = 20)
    private String complemento;
    // @Pattern(regexp="[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?", message="E-mail inválido")//if the field contains email address consider using this annotation to enforce field validation
    @Size(max = 30)
    private String email;
    @Size(max = 50)
    private String logradouro;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 70)
    private String nome;
    @Size(max = 20)
    private String numero;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 4)
    private String sigla;
    @Size(max = 12)
    private String telefone;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<EntidadesAdministradores> entidadesAdministradoresCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "entidades")
    private Collection<Bairros> bairrosCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<PessoasDeficiencias> pessoasDeficienciasCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<PessoasEnderecos> pessoasEnderecosCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<EntidadesLicencas> entidadesLicencasCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<PessoasContatos> pessoasContatosCollection;
    @OneToMany(mappedBy = "idEntidade")
    private Collection<Logradouros> logradourosCollection;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<Pessoas> pessoasCollection;
    @JoinColumn()
    @ManyToOne(optional = false)
    private Municipios idMunicipio;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "idEntidade")
    private Collection<PessoasCaracteristicas> pessoasCaracteristicasCollection;

    public Entidades() {
    }
          .... gets and sets . . 

    }

类 DistritosController

@RestController
@RequestMapping(value="/user")
public class DistritosController {

    @Autowired
    DistritosService distritosService; 


    @RequestMapping(method = RequestMethod.POST, value = "/distritos", consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Distritos> cadastrarDistritos(@RequestBody Distritos distritos) {
        Distritos distritosCadastrado = distritosService.cadastrar(distritos);
        return new ResponseEntity<Distritos>(distritosCadastrado, HttpStatus.CREATED);
    }

    @RequestMapping(method = RequestMethod.GET, value = "/distritos", produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Collection<Distritos>> buscarTodosDistritos() {
        Collection<Distritos> distritosBuscados = distritosService.buscarTodos();
        return new ResponseEntity<>(distritosBuscados, HttpStatus.OK);
    }

    @RequestMapping(method = RequestMethod.GET, value = "/distritos/{id}", produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Distritos> buscarDistritosPorId(@PathVariable int id) {
        Distritos distritos = distritosService.buscaPorId(id);
        return new ResponseEntity<>(distritos, HttpStatus.OK);
    }

    @RequestMapping(method = RequestMethod.DELETE, value = "/distritos/{id}")
    public ResponseEntity<Distritos> excluirDistritos(@PathVariable int id) {
        Distritos distritoEncontrado = distritosService.buscaPorId(id);
        if (distritoEncontrado == null) {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
        distritosService.excluir(distritoEncontrado);
        return new ResponseEntity<>(HttpStatus.OK);
    }

    @RequestMapping(method = RequestMethod.PUT, value = "/distritos", consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Distritos> alterarDistritos(@RequestBody Distritos distritos) {
        Distritos distritoAlterado = distritosService.alterar(distritos);
        return new ResponseEntity<Distritos>(distritoAlterado, HttpStatus.OK);
    }


}

最佳答案

有两个问题:

1。身份范围

两者都是 @JsonIdentityInfo 的应该是范围内的，因为你的两个类都有相同的生成器类型 - ObjectIdGenerators.PropertyGenerator.class .

Scope is used to define applicability of an Object Id: all ids must be unique within their scope; where scope is defined as combination of this value and generator type. Comparison is simple equivalence, meaning that both type generator type and scope class must be the same. Scope is used for determining how many generators are needed; more than one scope is typically only needed if external Object Ids have overlapping value domains (i.e. are only unique within some limited scope)

对于 Distritos :

@JsonIdentityInfo(scope = Distritos.class, generator = ObjectIdGenerators.PropertyGenerator.class, property = "idDistrito")

对于 Entidades :

@JsonIdentityInfo(scope = Entidades.class, generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEntidade")

2。字段命名

@JoinColumn()
@ManyToOne
private Entidades idEntidade;

以某种方式干扰

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
private Long idEntidade;

当您将完整的 Distritos 传递给 Jackson 反序列化器时对象(包含 Entidades 内部，如您的示例所示)。

我做了一些调试，发现 BeanDeserializer (按名称解析字段)无法反序列化属性字段，因为它与 id 字段同名，所以我更改了 idEntidade至 entidade在 Distritos类。

在这些更改之后，我的示例项目工作正常(因为我已经从您的类中删除了一些字段 - Distritos.idMunicipio、Distritos.idUf 以及来自 Entidades 的所有 Collection)。您必须检查其他类(例如 Municipios 和 Ufs )是否有相同的问题，并修复它们。

关于java - JSON 解析错误 : Already had POJO for id，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46493841/