hibernate3 one-ton-one总结之关联表关联实现one-to-one-优快云博客

本文介绍Hibernate3中通过关联表实现一对一关联的方法，并提供了一个具体的示例。该示例包括创建必要的数据库表、定义Java实体类及配置XML文件。

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在hibernate3中，one-to-one关联主要通过3种方式来实现：

(1)共享的关联主键

(2)主外键关联

(3)通过关联表关联

其中，第一和第二中关联很常见，第三种关联因为效率关系很少使用。

下面是通过关联表关联实现one-to-one的简单例子，通过关联表实现one-to-one在网上例子非常少，这个程序我也是试了N长时间才搞定的：

create table person (
 person_id bigint primary key,
 name varchar(255) not null
);

create table address(
 address_id bigint primary key,
 country varchar(255),
 city varchar(255),
 street varchar(255)
);

create table passport (
 passport_id bigint primary key,
 num varchar(255)
);

create table person_mid (
 person_id bigint,
 address_id bigint,
 passport_id bigint,
 unique(person_id),
 primary key(address_id, passport_id),
 foreign key (person_id) references person(person_id),
 foreign key (address_id) references address(address_id),
 foreign key (passport_id) references passport(passport_id)
);

package domain;

import java.io.Serializable;

public class Person implements Serializable {
	
	private Long id;
	private String name;
	private Address address;
	private Passport passport;
	
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Address getAddress() {
		return address;
	}
	public void setAddress(Address address) {
		this.address = address;
	}
	public Passport getPassport() {
		return passport;
	}
	public void setPassport(Passport passport) {
		this.passport = passport;
	}
}

package domain;

import java.io.Serializable;

public class Address implements Serializable {
	private Long id;
	private String country;
	private String city;
	private String street;
	private Person person;
	
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getCountry() {
		return country;
	}
	public void setCountry(String country) {
		this.country = country;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getStreet() {
		return street;
	}
	public void setStreet(String street) {
		this.street = street;
	}
	public Person getPerson() {
		return person;
	}
	public void setPerson(Person person) {
		this.person = person;
	}
}

package domain;

import java.io.Serializable;

public class Passport implements Serializable {
	
	private Long id;
	private String num;
	private Person person;
	
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getNum() {
		return num;
	}
	public void setNum(String num) {
		this.num = num;
	}
	public Person getPerson() {
		return person;
	}
	public void setPerson(Person person) {
		this.person = person;
	}
}

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="domain.Person" table="person" dynamic-insert="true" >
	
		<id name="id" column="person_id">
			<generator class="sequence" >
				<param name="sequence">seq</param>
			</generator>
		</id>
		
		<property name="name" column="name" not-null="true" />
		
		<join table="person_mid" optional="true" >
			<key column="person_id" />
			<many-to-one name="address" column="address_id" not-null="true" unique="true" cascade="all" />
			<many-to-one name="passport"  column="passport_id" not-null="true" unique="true" cascade="all" />
		</join>
		
	</class>
</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="domain.Address" table="address" dynamic-insert="true" >
	
		<id name="id" column="address_id">
			<generator class="foreign" >
				<param name="property">person</param>
			</generator>
		</id>
		
		<property name="country" column="country" not-null="true" />
		<property name="city" column="city" not-null="true" />
		<property name="street" column="street" not-null="true" />
		
		<join table="person_mid" optional="true">
			<key column="address_id" />
			<many-to-one name="person" column="person_id" not-null="true" unique="true" insert="false" update="false" />
		</join>
		
	</class>
</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="domain.Passport" table="passport" dynamic-insert="true" >
	
		<id name="id" column="passport_id">
			<generator class="foreign" >
				<param name="property">person</param>
			</generator>
		</id>
		
		<property name="num" column="num" not-null="true" />
		
		<join table="person_mid" optional="true">
			<key column="passport_id" />
			<many-to-one name="person" column="person_id" not-null="true" unique="true" insert="false" update="false" />
		</join>
		
	</class>
</hibernate-mapping>