java - Hibernate ManyToMany 加入

Question

我是 Hibernate 新手，我将它与 Spring 一起使用。我有下表:

@Entity
@Configurable
public class Location {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long locationid;

    private String locationName;

    @ManyToOne
    private Site site;

//getters setters skipped
}

@Entity
@Configurable
public class Site {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long siteid;

    private String siteName;

    @ManyToOne
    private Country country;
    //getters setters skipped
    }

@Entity
@Configurable
public class Country {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long countryid;

    private String countryName;
    @ManyToOne
    private Region region;
    //getters setters skipped
}

@Entity
@Configurable
public class Region {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long regionid;

    private String regionName;
    //getters setters skipped
}

public class Assets {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long assetId;


    @ManyToOne
    private Location location;
    //getters setters skipped
}

我想根据区域提取所有 Assets 。我该怎么做？

如何利用 Region --> Country --> Site --> Location 之间的关系并拉取相关记录？如何在不影响性能的情况下做到这一点？

或者我应该重新设计表格？

Answer 1

您可以通过 Assets 类中的 @NamedQuery 来完成它:
从断言 a 中选择一个，其中 a.location.site.contry.regin.reginName = :reginName

希望有帮助。