JPA hibernate 一对多无限循环双向关系问题

Question

我使用 JAP ( @Entity ) 在两个表之间建立了双向关系。 当我执行 Select throw repository.findAll()它会返回给我一个无限循环的对象内部和其他内部对象。

这里是第一个实体：

@Entity
@Table(name = "TIPOS_DOCUMENTOS_IDENTIDAD")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "TiposDocumentosIdentidad.findAll", query = "SELECT t FROM TiposDocumentosIdentidad t"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoId", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoId = :tidoId"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoDescripcion", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoDescripcion = :tidoDescripcion"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoSiglas", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoSiglas = :tidoSiglas")})
public class TiposDocumentosIdentidad implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "TIDO_TIDO_ID_SEQ")
    @Column(name = "TIDO_ID")
    private Integer tidoId;
    @Basic(optional = false)
    @Column(name = "TIDO_DESCRIPCION")
    private String tidoDescripcion;
    @Basic(optional = false)
    @Column(name = "TIDO_SIGLAS")
    private String tidoSiglas;
    
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "tidoId")
    private Collection<Personas> personasCollection;
.
.
@XmlTransient
    public Collection<Personas> getPersonasCollection() {
        return personasCollection;
    }

    public void setPersonasCollection(Collection<Personas> personasCollection) {
        this.personasCollection = personasCollection;
    }
.
.

第二实体：

@Entity
@Table(name = "PERSONAS")
@XmlRootElement

public class Person as implements Serializable {
private static final long serialVersionUID = 1L;


@Id
@Basic(optional = false)
@GeneratedValue(strategy = GenerationType.AUTO, generator = "PERSONAS_PERS_ID_SEQ")
@Column(name = "PERS_ID")
private Integer persId;
@Column(name = "PERS_DIGITO_VERIFICACION")
private String persDigitoVerificacion;
@Basic(optional = false)
@Column(name = "PERS_NUMERO_DOCUMENTO")
private String persNumeroDocumento;    
@Basic(optional = false)
@Column(name = "PERS_FECHA_CREACION")
@Temporal(TemporalType.TIMESTAMP)
private Date persFechaCreacion;
@PrePersist
public void prePersist() {
    persFechaCreacion = new Date();
}

@JoinColumn(name = "TIDO_ID", referencedColumnName = "TIDO_ID")
@ManyToOne(optional = false)    
private TiposDocumentosIdentidad tidoId;
.
.
.

这是 pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>co.com.personasProject</groupId>
    <artifactId>personasProject</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>personasProject</name>
    <description></description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.oracle.database.jdbc</groupId>
            <artifactId>ojdbc8</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--        <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
                <scope>provided</scope>
        </dependency>-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

无限结果

我该如何解决这个错误？ 我只有 q 行 int 两个表

Answer 1

尝试使用@JsonManagedReference和@JsonBackReference注释关系，让 Jackson 更好地处理双向关系：

@Entity
@Table(name = "TIPOS_DOCUMENTOS_IDENTIDAD")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "TiposDocumentosIdentidad.findAll", query = "SELECT t FROM TiposDocumentosIdentidad t"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoId", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoId = :tidoId"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoDescripcion", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoDescripcion = :tidoDescripcion"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoSiglas", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoSiglas = :tidoSiglas")})
public class TiposDocumentosIdentidad implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "TIDO_TIDO_ID_SEQ")
    @Column(name = "TIDO_ID")
    private Integer tidoId;
    @Basic(optional = false)
    @Column(name = "TIDO_DESCRIPCION")
    private String tidoDescripcion;
    @Basic(optional = false)
    @Column(name = "TIDO_SIGLAS")
    private String tidoSiglas;
    
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "tidoId")
    @JsonManagedReference
    private Collection<Personas> personasCollection;
.
.
    @XmlTransient
    public Collection<Personas> getPersonasCollection() {
        return personasCollection;
    }

    public void setPersonasCollection(Collection<Personas> personasCollection) {
        this.personasCollection = personasCollection;
    }
.
.

@Entity
@Table(name = "PERSONAS")
@XmlRootElement

public class Person as implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @Basic(optional = false)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "PERSONAS_PERS_ID_SEQ")
    @Column(name = "PERS_ID")
    private Integer persId;
    @Column(name = "PERS_DIGITO_VERIFICACION")
    private String persDigitoVerificacion;
    @Basic(optional = false)
    @Column(name = "PERS_NUMERO_DOCUMENTO")
    private String persNumeroDocumento;    
    @Basic(optional = false)
    @Column(name = "PERS_FECHA_CREACION")
    @Temporal(TemporalType.TIMESTAMP)
    private Date persFechaCreacion;
    @PrePersist
    public void prePersist() {
        persFechaCreacion = new Date();
    }

    @JoinColumn(name = "TIDO_ID", referencedColumnName = "TIDO_ID")
    @ManyToOne(optional = false)
    @JsonBackReference
    private TiposDocumentosIdentidad tidoId;
    .
    .
    .
}

假设您使用 Jackson 序列化为 JSON，这应该可以解决它。 您可以在https://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion阅读更多信息。

---

另一种选择是使用@JsonIdentityInfo如下（它也需要 Jackson）：

@Entity
@Table(name = "TIPOS_DOCUMENTOS_IDENTIDAD")
@JsonIdentityInfo(
  generator = ObjectIdGenerators.PropertyGenerator.class, 
  property = "tidoId")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "TiposDocumentosIdentidad.findAll", query = "SELECT t FROM TiposDocumentosIdentidad t"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoId", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoId = :tidoId"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoDescripcion", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoDescripcion = :tidoDescripcion"),
    @NamedQuery(name = "TiposDocumentosIdentidad.findByTidoSiglas", query = "SELECT t FROM TiposDocumentosIdentidad t WHERE t.tidoSiglas = :tidoSiglas")})
public class TiposDocumentosIdentidad implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "TIDO_TIDO_ID_SEQ")
    @Column(name = "TIDO_ID")
    private Integer tidoId;
    @Basic(optional = false)
    @Column(name = "TIDO_DESCRIPCION")
    private String tidoDescripcion;
    @Basic(optional = false)
    @Column(name = "TIDO_SIGLAS")
    private String tidoSiglas;
    
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "tidoId")
    private Collection<Personas> personasCollection;
.
.
    @XmlTransient
    public Collection<Personas> getPersonasCollection() {
        return personasCollection;
    }

    public void setPersonasCollection(Collection<Personas> personasCollection) {
        this.personasCollection = personasCollection;
    }
.
.

@Entity
@Table(name = "PERSONAS")
@XmlRootElement
@JsonIdentityInfo(
  generator = ObjectIdGenerators.PropertyGenerator.class, 
  property = "persId")
public class Person as implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @Basic(optional = false)
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "PERSONAS_PERS_ID_SEQ")
    @Column(name = "PERS_ID")
    private Integer persId;
    @Column(name = "PERS_DIGITO_VERIFICACION")
    private String persDigitoVerificacion;
    @Basic(optional = false)
    @Column(name = "PERS_NUMERO_DOCUMENTO")
    private String persNumeroDocumento;    
    @Basic(optional = false)
    @Column(name = "PERS_FECHA_CREACION")
    @Temporal(TemporalType.TIMESTAMP)
    private Date persFechaCreacion;
    @PrePersist
    public void prePersist() {
        persFechaCreacion = new Date();
    }

    @JoinColumn(name = "TIDO_ID", referencedColumnName = "TIDO_ID")
    @ManyToOne(optional = false)
    @JsonBackReference
    private TiposDocumentosIdentidad tidoId;
    .
    .
    .
}