Question

我在使用hibernate的一对多映射中遇到一个问题。

我有2个班级，人和地址。人通过地址（一对多）映射我想得到所有地址=“xxxx”;的人。如何使用 DetachedCriteria 准备此查询。下面我添加了一段来自我的dao类的代码。请帮我完成它。

Person.java

@Entity
@Table(name="PERSON")
public class Person {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="personId")
     private int id;
    @Column(name="personName")
    private String name;
    @OneToMany(cascade =CascadeType.ALL,fetch = FetchType.LAZY)
    @JoinColumn(name="personId") 
    private Set <Address> addresses;
}

Address.java

@Entity
@Table(name = "ADDRESS")
public class Address {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "addressId")
    private int id;
    @Column(name = "address",nullable=false)
    private String address;
    @ManyToOne(cascade =CascadeType.ALL)
    @JoinColumn(name="personId",nullable=false)
    private Person person;
}

我的DAO

DetachedCriteria c = DetachedCriteria.forClass(Person.class);
        List<Person> persnList =null;
        /*here i want add some restriction for
           fetch all person whose address = "abcd"
           here address is collection. how to set restriction in it ?.

           */
        persnList = getHibernateTemplate().findByCriteria(c);
        System.out.println(persnList.size());

从人员中选择*，其中Address.address =“xxxx”; 如何使用 DetachedCriteria 实现此目的？

Answer 1

DetachedCriteria c = DetachedCriteria.forClass(Person.class);
    List<Person> persnList =null;

DetachedCriteria addrCrit = c.createCriteria("addresses").addRestriction(Restrictions.eq("address","abcd"));
addrCrit.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);

    persnList = getHibernateTemplate().findByCriteria(c);
    System.out.println(persnList.size());

在主要标准上创建内部标准，这些标准将执行等效的内部联接。

基于子表的一对多分离条件父表提取

1 个答案: