如何使用@ConstructorResult 注解

Question

我有一些本機查詢，並希望將查詢執行的結果映射到非實體 POJO 類列表中：

@SqlResultSetMapping(
    name = "SomeMapping",
    classes = {
        @ConstructorResult(targetClass = SomeClass.class,
            columns = {
                @ColumnResult(name = "id", type = Integer.class),
                @ColumnResult(name = "NAME", type = String.class),
                @ColumnResult(name = "DATE_BEGIN", type = java.util.Date.class)
            }
        )
    }
)

public class SomeClass{
    private Integer id;
    private String name;
    private java.util.Date begDate;
    private java.util.Date endDate;

    public SomeClass(Integer id, String name, Date begDate){
        this.id = id;
        this.name = name;
        this.begDate = begDate;
    }

    //Getters & Setters ...
}

通常我想如何檢索查詢執行的結果：

String query = "SELECT " +
"A.id AS 'id', " +
"A.name AS 'NAME', " +
"A.begDate AS 'DATE_BEGIN' " + 
"FROM " +
"SomeTable A " +
"WHERE A.endDate < '2014-01-01'";

List<SomeClass> result = em.createNativeQuery(query, "SomeMapping").getResultList();

但我總是得到對象列表。 如何檢索我的 POJO-s 列表？

Answer 1

嘗試在實體上移動@SqlResultSetMapping實體。

Answer 2

無法重現，但您的代碼有一些問題。

• 在實體類上添加@SqlResultSetMapping
• 不要用'引用列別名

import java.util.Date;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@NoArgsConstructor
@AllArgsConstructor
@Data
public class SomeClass {
    private int id;
    private String name;
    private Date dateBegin;
}

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.ColumnResult;
import javax.persistence.ConstructorResult;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.SqlResultSetMapping;
import javax.persistence.Table;
import lombok.Getter;

@SqlResultSetMapping(
    name = "SomeMapping",
    classes = {
        @ConstructorResult(targetClass = SomeClass.class,
            columns = {
                @ColumnResult(name = "id", type = Integer.class),
                @ColumnResult(name = "NAME", type = String.class),
                @ColumnResult(name = "DATE_BEGIN", type = java.util.Date.class)
            })
    })
@Entity
@Table(name = "sometable")
@Getter
public class SomeEntity {

    @Id
    @Column(name = "id")
    private Integer id;

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

    @Column(name = "begdate")
    private Date begDate;

    @Column(name = "enddate")
    private Date endDate;
}

        final String query = "SELECT " +
            "A.id AS id, " +
            "A.name AS NAME, " +
            "A.begDate AS DATE_BEGIN " +
            "FROM " +
            "SomeTable A " +
            "WHERE A.endDate < '2014-01-01'";

        final List<SomeClass> result = em.createNativeQuery(query, "SomeMapping").getResultList();