JPA瞬态注释和JSON

Question

这是关于JPA瞬态注释的以下问题的后续操作 为什么JPA有@Transient注释？

我有一个我不想持久的瞬态变量,它标有瞬态注释.但是,当我想从我的其余控制器生成JSON时,此瞬态变量在输出的JSON中不可用.

POJO PublicationVO是直接的,没有花哨的属性,只有一些私有属性(持久化)有getter和setter以及1个瞬态变量.

@RequestMapping(value = { "{publicationId}"}, method = RequestMethod.GET, produces = "application/json")
@ResponseBody public PublicationVO getPublicationDetailsJSON(@PathVariable(value = "publicationId") Integer publicationId) {
    LOG.info("Entered getPublicationDetailsJSON - publicationId: " + publicationId);

    //Call method to get the publicationVO based on publicationId
    PublicationVO publicationVO = publicationServices.getPublicationByIdForRestCalls(publicationId);       
    LOG.info("publicationVO:{}", publicationVO);

    LOG.info("Exiting getPublicationDetailsJSON");
    return publicationVO;
}

PublicationVO如下

    package com.trinity.domain.dao;

import java.util.Calendar;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.Transient;

import com.fasterxml.jackson.annotation.JsonInclude;

@Entity
@Table(name = "publication")
public class PublicationVO {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    private Integer id;    
    @Column(name = "publicationName", unique = false, nullable = false, length = 200)
    private String publicationName;
    @Column(name = "publicationSource", unique = false, nullable = false, length = 45)
    private String publicationSource;

    @Column(name = "dateAdded", unique = false, nullable = false)
    private Calendar dateAdded;

    @Transient
    private float percentageProcessed;

    public Integer getId() {
        return id;
    }

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

    public String getPublicationName() {
        return publicationName;
    }

    public void setPublicationName(String publicationName) {
        this.publicationName = publicationName;
    }

    public String getPublicationSource() {
        return publicationSource;
    }

    public void setPublicationSource(String publicationSource) {
        this.publicationSource = publicationSource;
    }

    public Calendar getDateAdded() {
        return dateAdded;
    }

    public void setDateAdded(Calendar dateAdded) {
        this.dateAdded = dateAdded;
    }

    public float getPercentageProcessed() {
        return percentageProcessed;
    }

    public void setPercentageProcessed(float percentageProcessed) {
        this.percentageProcessed = percentageProcessed;
    }

    @Override
    public String toString() {
        return "PublicationVO [id=" + id + ", publicationName=" + publicationName + ", publicationSource=" + publicationSource + ", dateAdded=" + dateAdded
                + ", percentageProcessed=" + percentageProcessed + "]";
    }
}

当我在日志中看到publicationVO的调试语句时,瞬态变量包含在输出中,但在我的客户端代码中,瞬态变量不包含在json响应中.

任何帮助是极大的赞赏.

谢谢你,达米恩

Answer 1

我只是添加了JsonSerialize和JsonDeserialize注释.

@Transient
@JsonSerialize
@JsonDeserialize
private String myField;

Answer 2

与我在评论中告诉你的情况相反,由于杰克逊的Hibernate模块,杰克逊在用于序列化实体类的实例时似乎关心JPA注释.

在该模块中,有一个HibernateAnnotationIntrospector,文档引用为

简单的AnnotationIntrospector,它增加了对使用Transient表示可忽略字段(以及Jackson和/或JAXB注释)的支持.

正如您在此处所看到的,Jackson的默认行为是检查@Transient它可以找到的任何注释.

所以最后,您可以通过以下三种方式解决您的问题:

1. 配置Jackson(使用HibernateAnnotationIntrospector的setUseTransient方法)禁用@Transient注释检查(有关实现详细信息,请参阅此答案).
2. 使用另一个对象而不是PublicationVO方法的返回结果getPublicationDetailsJSON.您必须将值对象中的属性复制到某个时刻返回的对象.
3. 删除@Transient注释并保留属性(但我知道如果这不是你的选项,因为你可能有充分的理由让这个属性首先使JPA瞬态).

干杯

Answer 3

只是为了进一步补充m4rtin提供的答案

我采用了第一种方法 - 配置Jackson(使用HibernateAnnotationIntrospector的setUseTransient方法)来禁用对@Transient注释的检查.

在项目中,我follwed必须遵循以下螺纹的,以避免在非取懒对象序列化杰克逊 避免在非取懒对象杰克逊系列化

要将我的项目配置为不忽略瞬态注释,我按如下方式设置Hibernate4Module

        Hibernate4Module hm = new Hibernate4Module();
    hm.disable(Feature.USE_TRANSIENT_ANNOTATION);

感谢您对此m4rtin的帮助

Answer 4

我同时使用@Transient和@JsonProperty,然后就可以了!

@Transient
@JsonProperty
private String mapImageSrc;

Answer 5

它对我有用:

@Transient
@JsonProperty

在GETTER中(不在私有字段定义中)

和

@JsonAutoDetect(fieldVisibility = Visibility.ANY) 

注释课程