Spring JPA,MySQL-无法写入内容:通过引用链无限递归StackOverflowError

Question

我想知道我在这里做错了什么,因为我已经完成了加载类型,它不是递归的.但是我收到以下错误.当我尝试从访问对象访问getServerRequest()方法时.

WARN 6511 --- [nio-8080-exec-2] .wsmsDefaultHandlerExceptionResolver:写入HTTP消息失败:org.springframework.http.converter.HttpMessageNotWritableException:无法写入内容:无限递归(StackOverflowError)(通过参考链:com. biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collection.internal.PersistentBag [0] - > com.biscoind.domain.Visit [ "请求"] - > com.biscoind.domain.ServerRequest ["访问"] - > org.hibernate.collection.internal.PersistentBag [0] - > com.biscoind.domain.Visit [" 请求 "] - > com.biscoind.domain.ServerRequest [" 访问"] - > org.hibernate作为. collection.internal.PersistentBag [0] - > com.biscoind.domain.Visit [ "请求"] - > com.biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collection.internal.PersistentBag [0] - > com.biscoind.domain.Visit [ "请求"] - > com.biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collection.internal.PersistentBag [0] - > com.biscoind.domain.访问[ "请求"] - > com.biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collec tion.internal.PersistentBag [0] - > com.biscoind.domain.Visit [ "请求"] - > com.biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collection.internal.PersistentBag [0] - > com.biscoind.domain.Visit [ "请求"] - > com.biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collection.internal.PersistentBag [0] - > com.biscoind.domain.访问[ "请求"] - > com.biscoind.domain.ServerRequest [ "访问"] - > org.hibernate.collection.internal.PersistentBag [0] - >

我有以下映射类,

@Entity
@Table(name = "server_request")
public class ServerRequest {

    private Long id;
    private Date createdDate;
    private Date lastUpdatedDate;

    private List<Visit> visits = new ArrayList<Visit>();

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "server_request_id")
    public Long getId() {
        return id;
    }

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

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "request", cascade = CascadeType.ALL)
    public List<Visit> getVisits() {
        return visits;
    }

    public void setVisits(List<Visit> visits) {
        this.visits = visits;
    }

    public Date getCreatedDate() {
        return createdDate;
    }

    public void setCreatedDate(Date createdDate) {
        this.createdDate = createdDate;
    }

    public Date getLastUpdatedDate() {
        return lastUpdatedDate;
    }

    public void setLastUpdatedDate(Date lastUpdatedDate) {
        this.lastUpdatedDate = lastUpdatedDate;
    }
}

和,

@Entity
@Table(name = "user_visit")
public class Visit implements Serializable {

    private static final long serialVersionUID = 1L;

    private Long id;
    private ServerRequest request;
    private String status;
    private Date date;

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "user_visit_id")
    public Long getId() {
        return id;
    }

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

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "server_request_id", referencedColumnName = "server_request_id", nullable = false)
    public ServerRequest getRequest() {
        return request;
    }

    public void setRequest(ServerRequest request) {
        this.request = request;
    }

}

Answer 1

如果您正在使用Jackson并且转换器正在尝试编写JSON(堆栈没有明确说明),请@JsonIdentityInfo在getRequest()方法上添加注释.

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property="id", scope=ServerRequest.class)
@ManyToOne(fetch = FetchType.EAAGER)
@JoinColumn(name = "server_request_id", referencedColumnName = "server_request_id", nullable = false)
public ServerRequest getRequest() {
    return request;
}

这是Jackson在序列化/反序列化期间可以解析对象图中的循环依赖关系的方式.

一些技巧:

• 你不必申报FetchType.LAZY.这是默认完成的.
• 在您多对一,从恰克FetchType.EAAGER到FetchType.EAGER