[开发工具]第二十七弹，JPA如何使用注解实现一对多两端同时保存，并且查询同时查出

第二十七弹，JPA如何使用注解实现一对多两端同时保存，并且查询同时查出

一端PO如下：

/**
 * 事故管理-PO
 * @version 2021-5-14 09:16:36
 */
@Entity
@Table(name = "oc_accident",indexes = {@Index(name = "index_create_user",columnList = "create_user"),
        @Index(name = "index_update_user",columnList = "update_user")})
@ApiModel("事故管理")
public class OcAccidentPO implements Serializable {

    /**事故ID*/
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    @ApiModelProperty(value = "主键Id")
    private Integer id;

    /**创建时间*/
    @Basic
    @Column(name = "create_time")
    @JSONField(format = "yyyy-MM-dd HH:mm:ss")
    @ApiModelProperty(value = "创建时间")
    private Date createTime;

    /**创建人*/
    @Basic
    @Column(name = "create_user")
    @ApiModelProperty(value = "创建人")
    private Integer createUser;

    /**修改时间*/
    @Basic
    @Column(name = "update_time")
    @JSONField(format = "yyyy-MM-dd HH:mm:ss")
    @ApiModelProperty(value = "修改时间")
    private Date updateTime;

    /**修改人*/
    @Basic
    @Column(name = "update_user")
    @ApiModelProperty(value = "修改人")
    private Integer updateUser;

    /**事故明细*/
    @Valid
    @OneToMany(cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REMOVE,CascadeType.REFRESH}
            ,orphanRemoval = true,mappedBy="ocAccidentPO",fetch=FetchType.EAGER)
    private Set<OcAccidentDetailPO> ocAccidentDetailPOSet = new HashSet<OcAccidentDetailPO>();
	
	gettingsetting省略。。。

多端PO如下：

/**
 * 事故管理明细-PO
 * @version 2021-5-14 09:34:09
 */
@Entity
@Table(name = "oc_accident_detail")
@ApiModel("事故管理明细")
public class OcAccidentDetailPO implements Serializable {

    /**自增主键*/
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    @ApiModelProperty(value = "主键Id")
    private Integer id;

    /**创建时间*/
    @Basic
    @Column(name = "create_time")
    @JSONField(format = "yyyy-MM-dd HH:mm:ss")
    @ApiModelProperty(value = "创建时间")
    private Date createTime;

    /**创建人*/
    @Basic
    @Column(name = "create_user")
    @ApiModelProperty(value = "创建人")
    private Integer createUser;

    /**修改时间*/
    @Basic
    @Column(name = "update_time")
    @JSONField(format = "yyyy-MM-dd HH:mm:ss")
    @ApiModelProperty(value = "修改时间")
    private Date updateTime;

    /**修改人*/
    @Basic
    @Column(name = "update_user")
    @ApiModelProperty(value = "修改人")
    private Integer updateUser;

    /**事故*/
    @ManyToOne(cascade={CascadeType.REFRESH},fetch = FetchType.LAZY)
    @JoinColumn(name="accident_id")
    private OcAccidentPO ocAccidentPO;

	gettingsetting省略。。。

@JoinColumn(name=“accident_id”)注解代表会在多端数据库表自动生成accident_id字段

保存时如下：

/**
  * 添加/修改
  * @param ocAccidentPO 添加/修改对象
  * @param userId 当前用户id
  * @return 数据
  * @throws Exception 异常信息
  */
 @Override
 @Transactional(rollbackFor = Exception.class)
 public OcAccidentPO save(OcAccidentPO ocAccidentPO, Integer userId) throws Exception {
     if(ocAccidentPO == null){
         throw new Exception("要添加的数据不能为空");
     }
     if(ocAccidentPO.getOcAccidentDetailPOSet() != null && ocAccidentPO.getOcAccidentDetailPOSet().size() > 0){
         for(OcAccidentDetailPO item : ocAccidentPO.getOcAccidentDetailPOSet()){
             if(item.getId() != null){
                 //修改
                 item.setUpdateUser(userId);
                 item.setUpdateTime(Calendar.getInstance().getTime());
             }else{
                 //添加
                 item.setCreateTime(Calendar.getInstance().getTime());
                 item.setCreateUser(userId);
                 item.setUpdateUser(userId);
                 item.setUpdateTime(Calendar.getInstance().getTime());
             }
             item.setOcAccidentPO(ocAccidentPO);
         }
     }

     if(ocAccidentPO.getId() == null){
         //添加
         ocAccidentPO.setCreateTime(Calendar.getInstance().getTime());
         ocAccidentPO.setCreateUser(userId);
         ocAccidentPO.setUpdateUser(userId);
         ocAccidentPO.setUpdateTime(Calendar.getInstance().getTime());
     }else{
         //修改
         ocAccidentPO.setUpdateTime(Calendar.getInstance().getTime());
         ocAccidentPO.setUpdateUser(userId);
     }
     return ocAccidentDao.save(ocAccidentPO);
 }

需要注意的是，此功能为JPA级联保存修改删除，详情请参考jpa官网