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！