java - 使用 Hibernate 从数据库检索列表时出现 ClassCastException

Question

@Id
@Column(name="Item", unique = true, nullable = false)
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int itemId;

@Column(name="ItemName")
private String itemName;

@Column(name="ItemPrice")
private double itemPrice;

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

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

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "RestaurantId", nullable = false)
private Restaurant restaurant;

这是我的实体类，

public List<FoodItem> getFoodItems(Restaurant restaurant) {
    Session session=getSession();
    List<FoodItem> list=null;
    NativeQuery<?> query = session.createNativeQuery("SELECT " + 
            "   \"Item\"," + 
            "   \"ItemName\"," + 
            "   \"ItemPrice\"," + 
            "   \"RestaurantId\"," + 
            "   \"status\"," + 
            "   \"image\" " + 
            "FROM \"SYSTEM\".\"FoodItem\" where \"RestaurantId\"="+restaurant.getRestaurantId());
    list = (List<FoodItem>) query.getResultList();
    return  list;
}

当我运行此方法时，它不会返回 List<FoodItem>相反，它返回 List<Array>像这样，

[
[
    1,
    "Pasta",
    55,
    14,
    "Veg",
    null
],
[
    2,
    "Burger",
    35,
    14,
    "Veg",
    null
]
]

如果我尝试将列表中每个对象中的餐厅对象设置为 null，

for(int index=0 ;index< list.size();index++)
        list.get(index).setRestaurant(null);

我得到了 ClassCastException。我需要根据我的实体类的键:值对中的响应谁能帮我解决这个问题。谢谢。[更新]解决了!

Answer 1

您假设从 native 查询中获取对象数组列表。它不会为您构造开箱即用的类型对象。如果您想要类型化列表，则需要执行 JPQL 而不是 native 查询。

List<Object[]> listResults = query.getResultList();

迭代列表并构造类型化对象列表 -

List<FoodItem> foodItems = new ArrayList();

for (Object[] record : listResults) {

       FoodItem item = new FoodItem();
       // set values from record, do necessary casts as well.

       foodItems.add(item);

  }