我们有时在进行开发过程中，使用jpa的@Query注解去选择多张表然后返回一个DTO对象，这个时候我们需要特殊处理一下，因为默认情况下，你的jpa代码是不认DTO对象的。
- entity实体
@Entity
@Getter
@Setter
@Builder
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class OrderInfo extends EntityBase {
@Id
@GeneratedValue
private int id;
private int userId;
private String userName;
private double total;
private String shippingName;
private String shippingAddress;
private Date orderTime;
}
@Entity
@Getter
@Setter
@Builder
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class OrderItem extends EntityBase {
@Id
@GeneratedValue
private int id;
private int orderId;
private int productId;
private String productName;
private int count;
private double salePrice;
}
/**
* DTO对象
*/
@Getter
@Setter
@Builder
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class OrderList {
public int id;
private int userId;
private String userName;
private int productId;
private String productName;
private int count;
private double salePrice;
}
- repository方法
@Query("select new com.lind.microservice.productCenter.dto.OrderList" +
"( o.id,o.userId,o.userName,oi.productId,oi.productName,oi.count,oi.salePrice) " +
" from OrderInfo o " +
" join OrderItem oi on o.id=oi.orderId")
List<OrderList> getOrderInfos();
- 结果
[
{
"id": 5,
"userId": 3,
"userName": "lind",
"productId": 4,
"productName": "足球",
"count": 1,
"salePrice": 99
}
]