hibernate Annotation 双向one2one
花了三天时间研究了下 hibernate Annotation 双向关联
主控方 Husband.java,主控方即 Husband 来负责维护 双向 one2one 之间的关系，在Husband.java 中必须添加 cascade ,否则保存报错。
package com.yazuo.entity.annotation.one2one;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
import org.hibernate.annotations.CascadeType;
@Entity
@Table(name="husband")
@SequenceGenerator(name="husband_id_seq",sequenceName="husband_id_seq",allocationSize=1)
public class Husband implements Serializable{
/**
*
*/
private static final long serialVersionUID = 4920309776591073369L;
@Id
@GeneratedValue(generator="husband_id_seq",strategy=GenerationType.SEQUENCE)
private Integer id;
private String name;
@OneToOne(cascade=javax.persistence.CascadeType.ALL)
@JoinColumn(name="wife_id")
private Wife wife;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Wife getWife() {
return wife;
}
public void setWife(Wife wife) {
this.wife = wife;
}
}
被控方 Wife.java
package com.yazuo.entity.annotation.one2one;
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
@Entity
@Table(name="wife")
@SequenceGenerator(name="wife_id_seq",sequenceName="wife_id_seq",allocationSize=1)
public class Wife implements Serializable{
/**
*
*/
private static final long serialVersionUID = 8900644958432628054L;
@Id
@GeneratedValue(generator="wife_id_seq",strategy=GenerationType.SEQUENCE)
private Integer id;
private String name;
/*
* wife 端 加不加 fetch=FetchType.LAZY 打印的 sql 都是
* select
husband0_.id as id2_1_,
husband0_.name as name2_1_,
husband0_.wife_id as wife3_2_1_,
wife1_.id as id3_0_,
wife1_.name as name3_0_
from
husband husband0_
left outer join
wife wife1_
on husband0_.wife_id=wife1_.id
where
husband0_.wife_id=?
*/
@OneToOne(mappedBy="wife")
private Husband husband;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Husband getHusband() {
return husband;
}
public void setHusband(Husband husband) {
this.husband = husband;
}
}
Test.java
package com.yazuo.entity.annotation.one2one;
import org.hibernate.Hibernate;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.type.Type;
public class Test {
@org.junit.Test
public void add() throws Exception {
//Configuration cfg = new Configuration();
/*
* 使用注解时，hibernate.cfg.xml 中要添加 <mapping class="com.yazuo.annotation.entity">
* 且 configuration 要使用 AnntationConfiguration,否则报
* org.hibernate.MappingException: An AnnotationConfiguration instance is required to use <mapping class="com.yazuo.annotation.entity">
*/
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
Wife wife = new Wife();
wife.setName("wift");
Husband husband = new Husband();
husband.setName("husband");
wife.setHusband(husband);
husband.setWife(wife);
session.save(husband);
session.flush();
session.close();
sf.close();
}
@org.junit.Test
public void findWifeById() throws Exception {
/*
* 在 wift 和 husband 两端加 fetch=FetchType.LAZY,都会打印两条 sql,一条是查询 wift,一条是查询 husband
* 但 打印出来的 查询 husband 的 sql 不一样
* lazy 加在 wife 端，打印的查询 husband sql ：select from husband left outer join wife on
* lazy 加在 husband 端，打印的查询 husband sql ：select from husband where wife_id = ?
*/
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
String hql = "from Wife w where w.id = 17 ";
Wife wife = (Wife) session.createQuery(hql).list().get(0);
System.out.println(wife.getName());
wife.getHusband().getName();
// session.delete(wife);
session.flush();
session.close();
sf.close();
}
@org.junit.Test
public void findHusbandById() throws Exception {
/*
* 在 wift 和 husband 两端加 fetch=FetchType.LAZY,都会打印两条 sql,一条是查询 wift,一条是查询 husband
* 但 打印出来的 查询 husband 的 sql 不一样
* lazy 加在 wife 端，打印的查询 husband sql ：select from husband left outer join wife on
* lazy 加在 husband 端，打印的查询 husband sql ：select from husband where wife_id = ?
*/
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
String hql = "from Husband h where h.id = 10";
Husband husband = (Husband) session.createQuery(hql).uniqueResult();
System.out.println(husband.getName());
/*
* 将 husband.wife 的 fetch=lazy 是，只有在调用husband.getWife()时候才会执行
* select
wife0_.id as id3_1_,
wife0_.name as name3_1_,
husband1_.id as id2_0_,
husband1_.name as name2_0_,
husband1_.wife_id as wife3_2_0_
from
wife wife0_
left outer join
husband husband1_
on wife0_.id=husband1_.wife_id
where
wife0_.id=?
否则只会打印一条查询 husband 的 sql
*/
husband.getWife().getName();
//session.delete(husband); //设置级联，会将husband.wife 一并删除
//husband.getWife().setId(5); 改变 id 值报错
session.flush();
session.close();
sf.close();
}
@org.junit.Test
public void deleteWife() throws Exception {
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
// String hql = "from Wife w where w.id = 3 ";
// Wife wife = (Wife) session.createQuery(hql).list().get(0);
// Wife wife = new Wife(); 不能删除瞬时态的 wife
// wife.setId(4); //违反完整约束条件 (QIAN.FK4BB1A83B38791291) - 已找到子记录
// session.delete(wife); //wife 主键作为 husband 外键，不在wife 端设置 cascade 不能 delete
// Query query = session.createQuery("delete from Wife w where w.id =? and name=?").setParameters(new Object[]{9,"wift"}, new Type[]{Hibernate.INTEGER,Hibernate.STRING});
// Query query = session.createQuery("delete from Wife w where w.id in(:id)").setParameterList("id", new Integer[]{7,8});
Query query = session.createQuery("delete from Wife w where w.id =:id").setParameter("id",4);
query.executeUpdate();
// session.createQuery("delete from Wife w where w.id = 5").executeUpdate();
session.flush();
session.close();
sf.close();
}
@org.junit.Test
public void deleteHusband() throws Exception {
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
session.createQuery("delete from Husband h where h.id = 7").executeUpdate();
session.flush();
session.close();
sf.close();
}
@org.junit.Test
public void updateWife() throws Exception {
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
// String hql = "update Wife w set w.id=? where w.name =?";
// Query query = session.createQuery(hql).setParameters(new Object[]{17,"wift"}, new Type[]{Hibernate.INTEGER,Hibernate.STRING});
String hql = "update Wife w set w.name =? where w.id=?";
Query query = session.createQuery(hql).setParameters(new Object[]{"wife17",17}, new Type[]{Hibernate.STRING,Hibernate.INTEGER});
query.executeUpdate();
session.flush();
session.close();
sf.close();
}
@org.junit.Test
public void updateHusband() throws Exception {
AnnotationConfiguration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.openSession();
String hql = "update Husband h set h.name =? where h.id=?";
Query query = session.createQuery(hql).setParameters(new Object[]{"husband5",5}, new Type[]{Hibernate.STRING,Hibernate.INTEGER});
query.executeUpdate();
session.flush();
session.close();
sf.close();
}
}
小结：
1.Husband 里面有 Wife 的 id，Husband 为 主表，Wife 为从表
所以 Wife 的 OneToOne(mappedBy="wife")
2.在 Husband 的 OneToOne 中添加 fetch=FetchType.LAZY ，执行 select * from husband h where h.id = ?
结果打印一条语句
select
husband0_.id as id2_,
husband0_.name as name2_,
husband0_.wife_id as wife3_2_
from
husband husband0_
where
husband0_.id=1
只有在显示的调用 husband.getWife().getName() 的时候才会执行
select
wife0_.id as id3_1_,
wife0_.name as name3_1_,
husband1_.id as id2_0_,
husband1_.name as name2_0_,
husband1_.wife_id as wife3_2_0_
from
wife wife0_
left outer join
husband husband1_
on wife0_.id=husband1_.wife_id
where
wife0_.id=?
Hibernate:
select
wife0_.id as id3_1_,
wife0_.name as name3_1_,
husband1_.id as id2_0_,
husband1_.name as name2_0_,
husband1_.wife_id as wife3_2_0_
from
wife wife0_
left outer join
husband husband1_
on wife0_.id=husband1_.wife_id
where
wife0_.id=?
================================
select
husband0_.id as id2_0_,
husband0_.name as name2_0_,
husband0_.wife_id as wife3_2_0_
from
husband husband0_
where
husband0_.wife_id=?
Hibernate:
select
husband0_.id as id2_0_,
husband0_.name as name2_0_,
husband0_.wife_id as wife3_2_0_
from
husband husband0_
where
husband0_.wife_id=?
结果是打印三条语句！！！！！！！！！
而在从表中加不加 fetch=FetchType.LAZY，结果都是打印两条 sql！！！！！
3.cascade=CascadeType.ALL 加那一边，那一边才有权利级联增加实体到数据库，可以在主从两端都加cascade=CascadeType.ALL
4.wife 主键作为 husband 外键，不在wife 端设置 cascade 不能 delete
设置 cascade此时会执行两条 sql ，先删除 husband ，再删除 wife
5.调用 session.delete(husband) 和执行 delete from Husband h where h.id = 7 效果不一样
前者会删除 husband.wife ,后者不会
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主控方和被控方的区别:
当主控方和被控方两端都不加 cascade
session.save(husband) 会报错，org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before
flushing: com.yazuo.entity.annotation.one2one.Wife
因为主控方有义务维持关系，却又不能级联增加被控方，可以 cascade="save-update,persist"。
而 session.save(wife) 不会报错
所以主控方必须加 cascade