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hibernate之关于使用连接表实现一对多关联映射

2024-07-29 22:17:03   221人阅读


【Hibernate】之关于使用连接表实现一对多关联映射


基于中间表实现的一对多的关联映射，还是比较常见的。
Person(人)和Group(组)

Annotations配置

@Entity
@Table(name="t_group")
publicclass Group {
    private Integer id;
    private String name;
    private Set<Person> persons=newHashSet<Person>();
     
    @OneToMany
    @JoinTable(name="t_p",joinColumns={@JoinColumn(name="g_id")},
           inverseJoinColumns={@JoinColumn(name="p_id")})
    public Set<Person> getPersons() {
       returnpersons;
    }
    publicvoid setPersons(Set<Person> persons) {
       this.persons = persons;
    }
    @Id
    @GeneratedValue
    public Integer getId() {
       returnid;
    }
    publicvoid setId(Integer id) {
       this.id = id;
    }
    @Column(name="g_name")
    public String getName() {
       returnname;
    }
    publicvoid setName(String name) {
       this.name = name;
    }
}

@Entity
@Table(name="p_person")
publicclass Person {
    private Integer id;
    private String name;
    private Integer age;
    @Id
    @GeneratedValue
    public Integer getId() {
       returnid;
    }
    publicvoid setId(Integer id) {
       this.id = id;
    }
    @Column(name="p_name")
    public String getName() {
       returnname;
    }
    publicvoid setName(String name) {
       this.name = name;
    }
    @Column(name="p_age")
    public Integer getAge() {
       returnage;
    }
    publicvoid setAge(Integer age) {
       this.age = age;
    }
}



XML配置


<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/HibernateMapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="csg.hibernate.entity">
    <class name="Group" table="t_group">
       <id name="id">
           <column name="id"/>
           <generator class="native" />
       </id>
       <property name="name" />
       <set name="persons" table="t_p">
           <key column="g_id"/>
           <many-to-many column="p_id" class="Person" unique="true" />
       </set>
    </class>
</hibernate-mapping>


<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/HibernateMapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="csg.hibernate.entity">
    <class name="Person" table="t_person">
       <id name="id">
           <column name="id"/>
           <generator class="native" />
       </id>
       <property name="name" />
       <property name="age" />
    </class>
</hibernate-mapping>

在一对多的中间表映射中，Hibernate自动会转化为多对多来处理！




hibernate之关于使用连接表实现一对多关联映射


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