hibernate 一对一双向关联_主键

一对一映射分2种映射策略，一个是根据主键一样，另一个是根据外键一样。

 

注意到：one2one标签，只影响加载，不影响存储。

 

首先，讲主键。

 

1.单向一对一。

以Person类和IdCard类为例， 假设需求是根据Person找到IdCard，那么各个类如下：

 

package com.bjpowernode.hibernate.domain;
public class Person {
	private int id;
	private String name;
	private IdCard idCard;
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public IdCard getIdCard() {
		return idCard;
	}
	public void setIdCard(IdCard idCard) {
		this.idCard = idCard;
	}
}

 

Person配置文件：

 

<?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>

	<class name="com.bjpowernode.hibernate.domain.Person" table="t_person">
		<id name="id">
			<generator class="foreign">
				<param name="property">idCard</param>
			</generator>
		</id>
		
		<property name="name"/>
		<one-to-one name="idCard" constrained="true" />
	
	</class>
	
</hibernate-mapping>

 

IdCard类：

 

package com.bjpowernode.hibernate.domain;

import java.util.Set;


public class IdCard {
	private int id;
	private String name;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	/*public Set getStudents() {
		return students;
	}
	public void setStudents(Set students) {
		this.students = students;
	}*/
	
	
}

 

IdCard配置文件：

 

<?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>

	<class name="com.bjpowernode.hibernate.domain.IdCard" table="t_idcard">
		<id name="id">
			<generator class="native"/>
		</id>
		
		<property name="name"/>
		
	
	</class>
	
</hibernate-mapping>

 

 

-------------------------------------------------------------------------------------------------------------

 

2.双向一对一，主键策略

 

只要将IdCard中增加一个属性Person

 

package com.bjpowernode.hibernate.domain;



public class IdCard {
	private int id;
	private String name;
	private Person person;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public Person getPerson() {
		return person;
	}
	public void setPerson(Person person) {
		this.person = person;
	}
	
	
}

 

IdCard配置文件：

 

<?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>

	<class name="com.bjpowernode.hibernate.domain.IdCard" table="t_idcard">
		<id name="id">
			<generator class="native"/>
		</id>
		
		<property name="name"/>
		
		<one-to-one name="person"/>
	
	</class>
	
</hibernate-mapping>

 

至此，一对一双向主键策略完成。