java.lang.ClassCastException : [Ljava. lang.Object;不能转换到

Question

为什么在我的程序中会触发 java.lang.ClassCastException ？

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.App.Equip]

查询返回已回答(在 CheckLists calsse 中找到)但尚未由 Equip 对象回答的 list 列表

- 这是代码:

import org.json.simple.*;

    @SuppressWarnings("unchecked")

public JSONObject ListCheckListsNonETRepondu( long idEqp, long idmiss){

       Query query = manager.createNativeQuery("SELECT"
        + " checksl.id_check_lists as IdCheckLists,"
        + " checksl.titre_check as NomCheckLists,"
        + " checksl.recommendation as Recommendation, "
        + " resp.id_responsescheck as IdResponse, "
        + " resp.conformite as Conformite, "
        + " resp.date_response as DateResponse, "
        + " resp.missions_id as IdMission "
        + " FROM equipements eq "
        + " LEFT JOIN check_lists checksl"
        + " ON eq.id_equipements= checksl.equipements_id "
        + " LEFT JOIN responses_check_lists resp "
        + " ON checksl.id_check_lists = resp.check_lists_id "
        + " AND resp.missions_id ="+idmiss+""
        + " AND eq.id_equipements ="+idEqp
        + " ORDER BY checksl.id_check_lists"
         );

   List<Equip> res = query.getResultList();

   JSONObject obj = new JSONObject();

   for( Equip eq: res) //--The problem is here --
   {
       for(CheckLists checks : eq.getChecks())
       {
              obj.put("idCheckLists", checks.getIdCheckLists());
              obj.put("NomCheckLists", checks.getTitreCheck());
              obj.put("Recommendation", checks.getRecommendation());

              for(ResponsesCheckLists resp :checks.getResponsesChecks())
               {
                  obj.put("IdResponse",resp.getIdResponsesCHeck());
                  obj.put("DateResponse",resp.getDateResponse());
                  obj.put("Conformite",resp.isConformite());
                  obj.put("IdMission",resp.getRespmission().getIdMission());
               }
       }

   }
   return (JSONObject)obj; 
   }

-我的java类:

@Entity
public class CheckLists implements Serializable{

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="idCheckLists")
    private long idCheckLists;

    @Column(name="titreCheck")
    private String titreCheck;

    @Column(name="recommendation")
    private String recommendation;

    @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinColumn(name="equipements_id")
    @JsonBackReference
    private Equipements equipements;

    @OneToMany(mappedBy="CheckLts", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    //@Fetch(value = FetchMode.SUBSELECT)
    private Set<ResponsesCheckLists> ResponsesChecks;
 ..
}

//
@Entity
public class ResponsesCheckLists implements Serializable{

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="idResponsesCHeck")
    private long idResponsesCHeck;

    @Column(name="conformite")
    private boolean conformite;

    @Column(name="dateResponse")
    private String dateResponse;

    @ManyToOne
    @JoinColumn(name="missionsId")
    private Missions Respmission;

    @ManyToOne
    @JoinColumn(name="checkLists_Id")
    private CheckLists CheckLts;

....
}

//
@Entity
public class Equip implements Serializable{


    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="idEquipements")
    private long idEquipements;

    @Column(name="nomEq")
    private String nomEq;

    @Column(name="dateAjoutEq")
    private String dateAjoutEq;

    @Column(name="dateModificationEq")
    private String dateModificationEq;

    @OneToMany(mappedBy="equipements", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    //@Fetch(value = FetchMode.SUBSELECT)
    @JsonManagedReference
    private Set<CheckLists> checks;

    @ManyToOne
    @JoinColumn(name="actifs_id")
    private Actifs actifsEquipements;
}

我想以 Json 格式格式化我的 SQl 查询的结果。
这是 SQL 查询返回的内容 query.getResultList() :

[
   [
    1,
   "2.1 Create Separate Partition ",
   "Description.... ",
    1,
    false,
   "25/05/2017",
    15
  ],
  [
    2,
   "2.2 Set nodev option ",
  " Description:.... ",
    1,
    false,
   "25/05/2017",
   15
   ]
......
]

谁能介意给我一些建议？

非常感谢!!!

Answer 1

您的查询返回 List的 Object[]因为您没有选择 Equip实体，但您只选择 中的列:

   Query query = manager.createNativeQuery("SELECT"
    + " checksl.id_check_lists as IdCheckLists,"
    + " checksl.titre_check as NomCheckLists,"
    + " checksl.recommendation as Recommendation, "
    + " resp.id_responsescheck as IdResponse, "
    + " resp.conformite as Conformite, "
    + " resp.date_response as DateResponse, "
    + " resp.missions_id as IdMission "

Hibernate 不会转换 ResultSet结果为 Equip实体对象，结果将是 object 的数组s 因为 Hibernate 不会确定所选列的类型。

你需要遍历这个 List元素并转换每个 Object[]到 Equip手动对象。

编辑:

这是你应该如何实现它:

List<Object[]> res = query.getResultList();
List<Equip> list= new ArrayList<Equip>();
JSONObject obj = new JSONObject();

Iterator it = res.iterator();
while(it.hasNext()){
     Object[] line = it.next();
     Equip eq = new Equip();
     eq.setIdEquipement(line[0]);
     eq.setTitre(line[1]);
     eq.setDescription(line[2]);
     //And set all the Equip fields here
     //And last thing add it to the list

     list.add(eq);
}