hibernate之关于一对多单向关联映射


【hibernate】之关于一对多单向关联映射


基于外键的一对多关联映射!

一对多,Group(组)对于Person(人),一个组能够有多个人!ok?

Hibernate主要有两种配置方法。一种是Annotations 一种是XML


以下是Annotations的配置方法!

@Entity
@Table(name="t_group")
publicclass Group {
    private Integer id;
    private String name;
    private Set<Person> persons=newHashSet<Person>();//set不同意反复,最适合数据库模型
    @Id
    @GeneratedValue
    public Integer getId() {
       returnid;
    }
    publicvoid setId(Integerid) {
       this.id = id;
    }
    @Column(name="t_name")
    public String getName() {
       returnname;
    }
    publicvoid setName(Stringname) {
       this.name = name;
    }
    @OneToMany
     //加上@JoinColumn是为了防止Hibernate将一对多当做多对多来处理,产生中间表
    @JoinColumn(name="group_id")
    public Set<Person>getPersons() {
       returnpersons;
    }
    publicvoidsetPersons(Set<Person> persons){
       this.persons = persons;
    }
}

@Entity
@Table(name="t_person")
publicclass Person {
    private Integer id;
    private String name;
    private Integer age;
    @Id
    @GeneratedValue
    public Integer getId() {
       returnid;
    }
    publicvoid setId(Integerid) {
       this.id = id;
    }
    @Column(name="t_name")
    public String getName() {
       returnname;
    }
    publicvoid setName(Stringname) {
       this.name = name;
    }
    @Column(name="t_age")
    public Integer getAge() {
       returnage;
    }
    publicvoid setAge(Integerage) {
       this.age = age;
    }
}

XML配置一对多的单向关联映射
publicclass Person {
    private Integer id;
    private String name;
    private Integer age;
    public Integer getId() {
       returnid;
    }
    publicvoid setId(Integerid) {
       this.id = id;
    }
    public String getName() {
       returnname;
    }
    publicvoid setName(Stringname) {
       this.name = name;
    }
    public Integer getAge() {
       returnage;
    }
    publicvoid setAge(Integerage) {
       this.age = age;
    }
}

publicclass Group {
    private Integer id;
    private String name;
    private Set<Person> persons=newHashSet<Person>();//set不同意反复,最适合数据库模型
    public Integer getId() {
       returnid;
    }
    publicvoid setId(Integerid) {
       this.id = id;
    }
    public String getName() {
       returnname;
    }
    publicvoid setName(Stringname) {
       this.name = name;
    }
    public Set<Person>getPersons() {
       returnpersons;
    }
    publicvoidsetPersons(Set<Person> persons) {
       this.persons = persons;
    }
}

<?

xml version="1.0"?

> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping 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"> <key column="group_id"/> <one-to-many class="csg.hibernate.entity.Person"/> </set> </class> </hibernate-mapping>


<?

xml version="1.0"?

> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping 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>



Ok,一对多单向关联映射的Annotations和XML配置方法!



posted @ 2018-04-25 12:43  llguanli  阅读(175)  评论(1编辑  收藏  举报