如何在JavaSpring引导中获取值而不是对象

所以我想知道如何获得存储在Mysql中的值，而不是对象名

当我运行代码时，我得到：

[org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@5ba6132b, org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@28264619, org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@6ab78994, org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@50dd821f, org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@3b89ec64, org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@21856382, org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap@7728a50f]

代码如下：

@Data
@Entity
@Table(name="category")
@DynamicInsert
@DynamicUpdate
@NoArgsConstructor
@AllArgsConstructor
public class Category {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="category_id", columnDefinition = "INT(11)")
    private Integer Category_id;
    @Column(name="name",columnDefinition = "VARCHAR(20)")
    private String name;
    @Column(name = "parent",columnDefinition = "int(11)")
    private Integer parent;
}

这是我的分类码

package kr.co.ds.datastation.dsapi.repository;


public interface CategoryProjection {
    public String getLev1();
    public String getLev2();
    public String getLev3();
    public String getLev4();
}

这是我的

CategoryProjection

code

import java.util.List;


@Repository
public interface CategoryRepository extends JpaRepository<Category, Integer> {
    public static final String FIND_PROJECTS = "SELECT t1.name AS lev1, t2.name as lev2, t3.name as lev3, t4.name as lev4 FROM category AS t1 LEFT JOIN category AS t2 ON t2.parent = t1.category_id LEFT JOIN category AS t3 ON t3.parent = t2.category_id LEFT JOIN category AS t4 ON t4.parent = t3.category_id WHERE t1.name = 'ROOT'";

@Query(value = FIND_PROJECTS, nativeQuery = true)
public List<CategoryProjection> findByCategory();

}

private void mysql2() {

    this.categoryRepository.findByCategory();
}

这是我的

类别控制器
代码

import java.util.List;


@Repository
public interface CategoryRepository extends JpaRepository<Category, Integer> {
    public static final String FIND_PROJECTS = "SELECT t1.name AS lev1, t2.name as lev2, t3.name as lev3, t4.name as lev4 FROM category AS t1 LEFT JOIN category AS t2 ON t2.parent = t1.category_id LEFT JOIN category AS t3 ON t3.parent = t2.category_id LEFT JOIN category AS t4 ON t4.parent = t3.category_id WHERE t1.name = 'ROOT'";

@Query(value = FIND_PROJECTS, nativeQuery = true)
public List<CategoryProjection> findByCategory();

}

private void mysql2() {

    this.categoryRepository.findByCategory();
}

这是我的应用程序代码。
将以下代码添加到类别POJO类中，以使用值映射对象。此外，将getters setter添加到类中也是一个很好的实践

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        Category category = (Category) o;
        if (bot.id == null || id == null) {
            return false;
        }
        return Objects.equals(id, bot.id);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(id);
    }

    @Override
    public String toString() {
        return "{" +
            "id=" + id +
            ", name='" + name + "'" +
            ", parent='" + parent + "'" +
           '}';
    }

你的意思是什么？通常，您应该得到一个响应为
JSON
{“key”：“value”}
您想做什么？我不清楚您想要什么值。你的意图是什么