Hibernate一对一主键关联（基于annotation注解方式) -

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Hibernate一对一主键关联（基于annotation注解方式)

hibernate中一对一的关联有两种方式：一种是采用外键关联，另外一种是采用主键关联。

最近项目中用到一对一主键双向关联，并且是基于注解的方式。期间遇到一些问题，现在贴出来探讨探讨。

一个丈夫(husband)对应一个妻子(wife)，主要目标是在存储丈夫或者妻子时，关联的对象也被存储。具体代码如下：

husband类：

package cn.edu.dlnu.resources.model.entity;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;

@Entity
public class Husband {
private int id; private String name; private Wife wife; @Id @GeneratedValue //主键生成器 public int getId() { return id; } public String getName() { return name; } @OneToOne(cascade=CascadeType.ALL) @PrimaryKeyJoinColumn//这个注解只能写在主(生成ID)的一端 public Wife getWife() { return wife; } public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } public void setWife(Wife wife) { this.wife = wife; } } wife类：

package cn.edu.dlnu.resources.model.entity;

@Entity
public class Wife {
private int id; private String name; private Husband husband; @Id @GenericGenerator(name ="pkGenerator",strategy="foreign" ,parameters={@Parameter(name="property",value="husband")}) @GeneratedValue(generator="pkGenerator")

//wife的ID是根据husband的ID来赋值的，这里需要设置ID生成器的策略为foreign，参数中指定wife的ID是使用husband对象中的ID
public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public void setHusband(Husband husband) { this.husband = husband; } @OneToOne(cascade=CascadeType.ALL, mappedBy="wife")

public Husband getHusband() { return husband; } } OneToOnePKTest类：

package cn.edu.dlnu.resources.model.entity;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import cn.edu.dlnu.resources.model.entity.Husband;
import cn.edu.dlnu.resources.model.entity.Wife;

public class OneToOnePKTest {
private static SessionFactory sessionFactory; @BeforeClass public static void beforeClass() { sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); } @AfterClass public static void afterClass() { sessionFactory.close(); } @Test public void testSave(){ Session s = sessionFactory.getCurrentSession(); s.beginTransaction(); Husband h = new Husband(); Wife w = new Wife(); w.setName("w"); h.setName("h");

h.setWife(w); w.setHusband(h); s.save(w); s.getTransaction().commit(); }

@Test
public void testSchemaExport() { new SchemaExport(new AnnotationConfiguration().configure()).create(false, true); } public static void main(String[] args) { beforeClass(); new OneToOnePKTest().testSave(); afterClass(); } }

hibernate生成的数据库表：create table Husband (
id integer not null auto_increment, name varchar(255), primary key (id) )；

create table Wife (
id integer not null, name varchar(255), primary key (id) ) 运行testSave()，方法后数据库中husband 与 wife表中记录的主键一致。

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