spring - 嵌套异常是 org.hibernate.HibernateException : Could not instantiate resultclass

Question

出了什么问题？

public List < ReportDTO> listProductAll() {
    String sql 
            = "select "
            + "ip.product_name as productName, "
            + "ip.base_price as basePrice, "
            + "iu.username as username "
            + "from tb_buy a  "
            + "left join in_product ip on a.id_product = ip.product_id "
            + "left join im_users iu on a.id_user = iu.user_id ";
    Query q = identifyServer.getCurrentSession().createSQLQuery(sql)
            .addScalar("productName")
            .addScalar("basePrice")
            .addScalar("username")
            .setResultTransformer(Transformers.aliasToBean(ReportDTO.class));
    return q.list();
}

public class ReportDTO {

    private String productName;
    private Double basePrice;
    private String username;

    public ReportDTO(String productName, Double basePrice, String username) {
        this.productName = productName;
        this.basePrice = basePrice;
        this.username = username;
    }
// getter setter

org.springframework.orm.jpa.JpaSystemException: Could not instantiate resultclass: ReportDTO; nested exception is org.hibernate.HibernateException: Could not instantiate resultclass: ReportDTO

解决 公共(public) ReportDTO() {}

Answer 1

Hibernate 要求所有实体都有一个默认的无参数构造函数。
如果您的实体类没有它，或者它不是公共(public)的，您将收到此异常。