使用JPA自定义VO接收返回结果集(unwrap) 使用JPA自定义VO接收返回结果集

JPA自定义VO接收返回结果集(unwrap)
JPA返回自定义VO

JPA自定义VO接收返回结果集(unwrap) JPA跟mybitis比较，简单的业务搜索是方便的，但是设计到复杂的SQL搜索时，我们需要自定义SQL。
1.@Query直接写SQL,缺点是无法动态的组装条件
2.JPA的Specification对象动态组装where搜索条件
3.entityManager执行CriteriaBuilder
4.entityManger直接使用createNativeQuery，执行原生SQL。这里设计到返回结果集的承载体必须是数据库对应的实体。
这里说一个自定义的VO承接返回结果集的方法

ProjectAttendanceEntity@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id; @Column(name = "f_id")private Long fId; @Column(name = "user_id")private Integer userId; @Column(name = "zh_name")private String zhName; @Column(name = "po_code")private String poCode; @Column(name = "po_name")private String poName; @Column(name = "punch_date")private String punchDate; @Column(name = "is_original")private String isOriginal; @Column(name = "attendance_hours")private String attendanceHours; @Column(name = "work_hours")private String workHours; @Column(name = "punch_area")private String punchArea;

结果集承接VO (AttendancePoSzVO)

private String poId; private String poName; private String zhName;

【使用JPA自定义VO接收返回结果集(unwrap)】执行接口：

/*** 批量修改项目名称* @return*/@PostMapping("/po/sz/batch/{project}/{pn}/{ps}")public PageResultVO findBatchPoInfoByUserIdAndDate(@RequestBody List ids,@PathVariable String project,@PathVariable Integer pn,@PathVariable Integer ps){log.info("url:/po/sz/batch/"+"|param:"+ids); //通过id查询数据List projects = projectAttendanceEntityRepository.findByIdIn(ids); //获取SQLString sql = getSQL(projects,pn,ps); Query query = entityManager.createNativeQuery(sql); List list = query.unwrap(NativeQuery.class).setResultTransformer(Transformers.aliasToBean(AttendancePoSzVO.class)).getResultList(); //初始化结果集List result = new ArrayList<>(); for(AttendancePoSzVO poSz : list){result.add(new DropDownVO(poSz.getPoName(),poSz.getPoId())); }return new PageResultVO(GlobalReturnCode.SUCCESS_CODE,"SUCCESS",ps,pn,result); } /*** 组装查询SQL* @return*/public String getSQL(List poStatus, Integer pn, Integer ps){StringBuilder sql = new StringBuilder("SELECT DISTINCT res.po_id as poId,res.po_name as poName, GROUP_CONCAT(DISTINCT res.user_id) AS zhName "); sql.append(" FROM ("); sql.append(" SELECT tt.po_name,tt.po_id,tt.user_id"); sql.append(" FROM sie_sz_po_attendance_v tt "); sql.append(" WHERE"); for(ProjectAttendanceEntity po : poStatus){sql.append("(tt.user_id = ").append(po.getUserId()).append(" and tt.rt_begin_date <= '").append(po.getPunchDate()).append("' and tt.rt_end_date >= '").append(po.getPunchDate()).append("') OR "); }//截掉最后一个ORsql = new StringBuilder(sql.substring(0,sql.length()-3)); sql.append(" ) res"); sql.append(" GROUP BY res.po_name,res.po_id"); sql.append(" HAVING "); for(ProjectAttendanceEntity po : poStatus){sql.append(" INSTR(zhName,").append(po.getUserId()).append(") >0").append(" AND "); }//截取最后一个ANDsql = new StringBuilder(sql.substring(0,sql.length()-4)); sql.append(" LIMIT ").append(pn).append(",").append((pn+1)*ps); return sql.toString(); }

核心代码：

List list = query.unwrap(NativeQuery.class).setResultTransformer(Transformers.aliasToBean(AttendancePoSzVO.class)).getResultList();

但是这里的 setResultTransformer 已经过时了。
所以接下来寻找 setResultTransformer的替代API。

JPA返回自定义VO 最近做项目用到了JPA，很多地方需要返回自定义vo，最开始用@Query注解返回自定义List，在用forEach遍历存入List实在是不方便，找了一些资料做下笔记。
一般需要返回自定VO都是做连表动态查询，下面直接贴测试代码
User（Entity）

@Data@Entity@Table(name = "jpa_user")@AllArgsConstructor@NoArgsConstructor@Accessors(chain = true)public class User {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Integer id; @Column(name ="name")private String name; @Column(name ="age")private Integer age; @Column(name ="sex")private String sex; @Column(name ="card")private String card; @Column(name ="children")private Boolean children; }

UserRespDto(自定义VO)

@Datapublic class UserRespDto implements Serializable {private String myname; private String mycard; }

JPA接口不说了，继承JpaRepository和JpaSpecificationExecutor就行
测试

/*** 返回Entity对象，要求是数据库中字段全部查询即findAll或者理解为select **/@Testpublic void t2() {StringBuilder sb = new StringBuilder(); sb.append("select * from jpa_user where 1=1 "); //自行根据条件动态拼接，仅做演示sb.append("and name like '%李%' "); Query nativeQueryPo = entityManager.createNativeQuery(sb.toString(), User.class); List resultList = nativeQueryPo.getResultList(); System.out.println(resultList); }/*** 返回自定义VO对象，要求是查询别名必须和VO中属性名一致*/@Test//注意，很重要，事务必须开启，不开启会报错提示无法转化，具体原因和动态代理有关系@Transactional(readOnly = true)public void t3() {StringBuilder sb = new StringBuilder(); sb.append("select name myname,card mycard from jpa_user where 1=1 "); //自行根据条件动态拼接，仅做演示sb.append("and name like '%李%' "); Query nativeQuery = entityManager.createNativeQuery(sb.toString()); List list = nativeQuery.unwrap(NativeQueryImpl.class).setResultTransformer(Transformers.aliasToBean(UserRespDto.class)).list(); System.out.println(list); }

以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。