Hibernate一对一关联(共享主键)

一对一关联，在两个表中都由主键或外键关联另一个表中的一条记录。

比如一个人用户表，包含的信息很多，而在使用的时候，很多字段的信息使用并不是很频繁，这种情况下，不常使用的字段就可以单独成一张表，主要还是为了提高访问数据库的性能！

package com.pojo;
public class User implements java.io.Serializable {
	private static final long serialVersionUID = 3877915998065689256L;
	private Long id;
	private String username;
	private String password;
	//一对一关联
	private Profile profile;
	public Profile getProfile() {
		return profile;
	}
	public void setProfile(Profile profile) {
		this.profile = profile;
	}
	public User() {
	}
	public Long getId() {
		return this.id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getUsername() {
		return this.username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return this.password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

package com.pojo;
public class Profile implements java.io.Serializable {
	private static final long serialVersionUID = -9070015557361756382L;
	private Long id;
	private String email;
	private String phone;
	private String address;
	//关联User
	private User user;
	public User getUser() {
		return user;
	}
	public void setUser(User user) {
		this.user = user;
	}
	public Profile() {
	}
	public Long getId() {
		return this.id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getEmail() {
		return this.email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getPhone() {
		return this.phone;
	}
	public void setPhone(String phone) {
		this.phone = phone;
	}
	public String getAddress() {
		return this.address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
}

一对一的关联配置相对来说比较简单的，主要还是得注意主键的生成

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.pojo.User" table="USERS" schema="ZM">
        <id name="id" type="java.lang.Long">
            <column name="ID" precision="4" scale="0" />
            <generator class="increment"></generator>
        </id>
        <property name="username" type="java.lang.String">
            <column name="USERNAME" length="100" />
        </property>
        <property name="password" type="java.lang.String">
            <column name="PASSWORD" length="100" />
        </property>
        
        <!-- 一对一关联 -->
        <one-to-one name="profile" class="com.pojo.Profile"></one-to-one>
    </class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.pojo.Profile" table="PROFILE" schema="ZM">
        <id name="id" type="java.lang.Long">
            <column name="ID" precision="4" scale="0" />
       <!-- 主键外键生成 -->
       <generator class="foreign">
       <param name="property">user</param>
       </generator>
        </id>
        <property name="email" type="java.lang.String">
            <column name="EMAIL" length="100" />
        </property>
        <property name="phone" type="java.lang.String">
            <column name="PHONE" length="100" />
        </property>
        <property name="address" type="java.lang.String">
            <column name="ADDRESS" length="100" />
        </property>
        <one-to-one name="user" class="com.pojo.User"></one-to-one>
    </class>
</hibernate-mapping>

就这样，一对一关联就配置完成，下面可以来测试：

package com.test;
import org.hibernate.Session;
import com.pojo.Profile;
import com.pojo.User;
import com.util.HibernateManager;
public class Test2 {
	/**
	 * beckham  
	 *  Dec 15, 2009   2:24:21 PM 
	 */
	public static void main(String[] args) {
		Test2.load() ;
	}
	public static void add(){
		Session session = HibernateManager.openSession() ;
		
		User u = new User() ;
		u.setUsername("张三") ;
		u.setPassword("abcdefg") ;
		
		Profile p = new Profile() ;
		p.setAddress("西里小区"); 
		p.setEmail("[e-mail]") ;
		p.setPhone("111111") ;
		p.setUser(u) ;
		u.setProfile(p) ;
		
		try {
	        session.save(p);
			session.save(u) ;
		    HibernateManager.closeSession() ;
		} catch (Exception e) {
			HibernateManager.rollbackTransaction() ;
		}
 		
		
	}
	
	public static void load(){
		Session session = HibernateManager.openSession() ;
		long a = new Long(1) ;
		User user = (User)session.load(User.class,a) ;
		
		System.out.println(""+user.getUsername());
		System.out.println(""+user.getPassword());
		System.out.println(""+user.getId());
		System.out.println(""+user.getProfile().getId());
		System.out.println(""+user.getProfile().getAddress());
		System.out.println(""+user.getProfile().getEmail());
		System.out.println(""+user.getProfile().getPhone());
		
		try {
		    HibernateManager.closeSession() ;
		} catch (Exception e) {
			HibernateManager.rollbackTransaction() ;
		}
 		
		
	}
}

测试结果：

Hibernate:
select
user0_.ID as ID3_2_,
user0_.USERNAME as USERNAME3_2_,
user0_.PASSWORD as PASSWORD3_2_,
profile1_.ID as ID2_0_,
profile1_.EMAIL as EMAIL2_0_,
profile1_.PHONE as PHONE2_0_,
profile1_.ADDRESS as ADDRESS2_0_,
user2_.ID as ID3_1_,
user2_.USERNAME as USERNAME3_1_,
user2_.PASSWORD as PASSWORD3_1_
from
ZM.USERS user0_
left outer join
ZM.PROFILE profile1_
on user0_.ID=profile1_.ID
left outer join
ZM.USERS user2_
on profile1_.ID=user2_.ID
where
user0_.ID=?
张三
abcdefg
1
1
西里小区
[e-mail]
111111