我有一个由 spring mvc4 + hibernate5 配置的企业项目，它的所有关系都是渴望的并且性能非常糟糕......所以我正在逐步将所有渴望的关系转变为惰性......但我看到了很多错误在每一步中......它有时工作正常，有时不......

在此示例中，HeaderFromStore 是 RequestHeaders 的实例和 RequestLine 的子项。 DeliveryPoint 是 requestHeader 的子项，我不想获取 requestHeader 的 deliveryPoint...但是如果不在选择查询中使用它，则无法获取 HeaderFromStore !!

我使用了这个查询，但出现错误!

select m from MAMRequestLines m join fetch  m.mamRequestHeaders r 
left join fetch m.requestHeaderFromStore rr where m.id =:id

如果我使用这个查询我不会得到错误

select m from MAMRequestLines m join fetch  m.mamRequestHeaders r
left join fetch m.requestHeaderFromStore rr
join fetch rr.mamDeliveryPoints
left join fetch r.mamDeliveryPoints
join fetch where m.id =:id

请求行.java

@Entity(name = "RequestLines")
@Table(name = "_REQUEST_LINES")
//@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property = "@id")
public class RequestLines extends Entity implements Serializable {

    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    private RequestHeaders requestHeaders;

    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    private RequestHeaders requestHeaderFromStore;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "_REQUEST_Line_SEQ")
    @SequenceGenerator(name = "_REQUEST_Line_SEQ", sequenceName = "_REQUEST_Line_SEQ")
    @Column(name = "REQUEST_LINE_ID")
    public Long getId() {
        return id;
    }

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

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "REQUEST_HEADER_ID", nullable = false)
    public RequestHeaders getRequestHeaders() {
        return RequestHeaders;
    }

    public void setRequestHeaders(RequestHeaders requestHeaders) {
        this.RequestHeaders = requestHeaders;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "REQUEST_HEADER_FROM_STORE")
    public RequestHeaders getRequestHeaderFromStore() {
        return requestHeaderFromStore;
    }

    public void setRequestHeaderFromStore(RequestHeaders requestHeaderFromStore) {
        this.requestHeaderFromStore = requestHeaderFromStore;
    }

}

RequestHeader.java

 @Entity(name = "RequestHeaders")
    @Table(name = "REQUEST_HEADERS")
    //@JsonInclude(JsonInclude.Include.NON_EMPTY)
    public class RequestHeaders extends Entity implements Serializable {

        private long id;



    // @JsonInclude(JsonInclude.Include.NON_EMPTY)
      // @JsonIgnore
        private DeliveryPoints DeliveryPoints;


        @JsonIgnore
        private Set<RequestLines> RequestLinesSet;


        @Id
        @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "_REQUEST_HEADERS_SEQ")
        @SequenceGenerator(name = "_REQUEST_HEADERS_SEQ", sequenceName = "_REQUEST_HEADERS_SEQ")
        @Column(name = "REQUEST_HEADER_ID")
        public long getId() {
            return id;
        }

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



        @ManyToOne(fetch = FetchType.LAZY)
        @JoinColumn(name = "DELIVERY_POINT_ID", nullable = false)
        public DeliveryPoints getDeliveryPoints() {
            return DeliveryPoints;
        }

        public void setDeliveryPoints(DeliveryPoints DeliveryPoints) {
            this.DeliveryPoints = DeliveryPoints;
        }


        @OneToMany(mappedBy = "RequestHeaders", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
        @OnDelete(action = OnDeleteAction.CASCADE)
        public Set<RequestLines> getRequestLinesSet() {
            return RequestLinesSet;
        }

        public void setRequestLinesSet(Set<RequestLines> RequestLinesSet) {
            this.RequestLinesSet = RequestLinesSet;
        }


    }

异常(exception):

No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: domain.RequestLine["HeaderFromStore"]->.domain.RequestHeaders["DeliveryPoint"]->domain.DeliveryPoint_$$_jvst393_f["handler"])

请注意，我使用了 JsonIgnore 和 JsonInclude(在字段和类上)，但它们都不起作用......

编辑: 我终于找到了这个解决方案来避免异常和忽略不需要的属性。 我将这部分代码添加到 WebMvcConfig extends WebMvcConfigurerAdapter 类:

{
public MappingJackson2HttpMessageConverter jacksonMessageConverter(){
    MappingJackson2HttpMessageConverter messageConverter = new  MappingJackson2HttpMessageConverter();

    ObjectMapper mapper = new ObjectMapper();
    //Registering Hibernate4Module to support lazy objects
    mapper.registerModule(new Hibernate4Module());

    messageConverter.setObjectMapper(mapper);
    return messageConverter;

}

@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    //Here we add our custom-configured HttpMessageConverter
    converters.add(jacksonMessageConverter());
    super.configureMessageConverters(converters);
}

但我现在有另一个问题...所有发布请求都将在请求正文中收到 null 属性...例如，在这段代码中，输入中“requestHeaders”的所有属性都是 null 或空的!

 @RequestMapping(value = "/requestHeader/", method = RequestMethod.POST, consumes = {"application/json"})
    public ResponseEntity<Void> createRequestHeaders(@RequestBody RequestHeaders requestHeaders, UriComponentsBuilder ucBuilder) {

        requestHeaders.setDeliveryPoints(deliveryPointsService.find(requestHeaders.getDeliveryPointsId()));

        requestHeadersService.add(requestHeaders);
        HttpHeaders headers = new HttpHeaders();

        return new ResponseEntity<Void>(headers, HttpStatus.CREATED);

    }

最佳答案

您应该在类定义的顶部添加与此注释相关的每个实体。

@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})

详情说明here和 here

希望这些能解决您的问题。

关于java - spring mvc 4 + hibernate 5 懒加载配置，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46806570/