我们先来看代码:
Dao层根据id查询方法
@Query("select * from test where id = ?")
PermissionsLogDTO findByPermissionsId(Long id);
用来接收的实体类:
public class PermissionsLogDTO {
/**
* 日志ID
*/
private Integer logId;
/**
* 流程表ID
*/
private Long permissionsId;
/**
* 最后改变时间
*/
private Date lastChangetime;
/**
* 改变人
*/
private String updateUserid;
/**
* 状态
*/
private Integer status;
/**
* 租户id
*/
private Integer tenantId;
}
Controller层代码:
@Autowired
PermissionsLogRepository permissionsLogRepository;
@GetMapping("/test")
public PermissionsLogDTO rtest(String id) {
long lid = Long.parseLong(id);
PermissionsLogDTO byPermissionsId = permissionsLogRepository.findByPermissionsId(lid);
log.info(byPermissionsId.toString());
return byPermissionsId;
}
postman访问:
直接报错:
java.lang.reflect.InvocationTargetException
这个时候我们在接收类里面加上全参构造:
public PermissionsLogDTO(Integer logId, Long permissionsId, Date lastChangetime, String updateUserid, Integer status, Integer tenantId) {
this.logId = logId;
this.permissionsId = permissionsId;
this.lastChangetime = lastChangetime;
this.updateUserid = updateUserid;
this.status = status;
this.tenantId = tenantId;
}
再次访问:
PermissionsLogDTO{logId=102, permissionsId=1413043148779294720, lastChangetime=2021-07-08 15:51:54.0, updateUserid='04987', status=1, tenantId=2288}
成功接收到了参数。
综上所述:Sql语句查询出来的数据可以用实体类接收的条件就是通过全参的构造函数
将查出来的值一一赋值到实体类中。
为了进一步论证这个结果,我们将构造器中的lastchangetime删除掉:
public PermissionsLogDTO(Integer logId, Long permissionsId, String updateUserid, Integer status, Integer tenantId) {
this.logId = logId;
this.permissionsId = permissionsId;
this.updateUserid = updateUserid;
this.status = status;
this.tenantId = tenantId;
}
输出来的结果显示:
PermissionsLogDTO{logId=102, permissionsId=1413043148779294720, lastChangetime=null, updateUserid='04987', status=1, tenantId=2288}
很明显lastChangetime的值变为空了。