Hibernate,JPA注解@EmbeddedId
定义组合主键的几种语法:
- 将组件类注解为@Embeddable,并将组件的属性注解为@Id
- 将组件的属性注解为@EmbeddedId
- 将类注解为@IdClass,并将该实体中所有属于主键的属性都注解为@Id
组合主键使用一个可嵌入的类作为主键表示,因此你需要使用@Id 和@Embeddable两个注解. 还有一种方式是使用@EmbeddedId注解.注意所依赖的类必须实现 serializable以及实现equals()/hashCode()方法.
用例代码如下:
- 数据库DDL语句
1 create table DOG 2 ( 3 dog_name VARCHAR2(255 CHAR) not null, 4 id_no VARCHAR2(255 CHAR) not null, 5 mobile VARCHAR2(255 CHAR), 6 create_time TIMESTAMP(6), 7 update_time TIMESTAMP(6) 8 )
- hibernate.cfg.xml
1 <?xml version="1.0" encoding="utf-8" ?> 2 <!DOCTYPE hibernate-configuration 3 PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" 4 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> 5 <hibernate-configuration> 6 <session-factory> 7 <!-- 数据库驱动配置 --> 8 <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property> 9 <property name="connection.driver_class">oracle.jdbc.OracleDriver</property> 10 <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property> 11 <property name="connection.username">wxuatuser</property> 12 <property name="connection.password">xlh</property> 13 <property name="show_sql">true</property> 14 <!-- 自动执行DDL属性是update,不是true --> 15 <property name="hbm2ddl.auto">update</property> 16 <!-- hibernate实体类 --> 17 18 <mapping class="a5_EmbeddedId.Dog"/> 19 20 </session-factory> 21 </hibernate-configuration>
- java类
实体类 - 基类
package model; import java.io.Serializable; import java.util.Date; import javax.persistence.Column; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.MappedSuperclass; import org.hibernate.annotations.GenericGenerator; /** * 实体类 - 基类 */ @MappedSuperclass public class BaseEntity implements Serializable { private static final long serialVersionUID = -6718838800112233445L; private String id;// ID private Date create_time;// 创建日期 private Date update_time;// 修改日期 @Id @Column(length = 32, nullable = true) @GeneratedValue(generator = "uuid") @GenericGenerator(name = "uuid", strategy = "uuid") public String getId() { return id; } public void setId(String id) { this.id = id; } @Column(updatable = false) public Date getCreate_time() { return create_time; } public void setCreate_time(Date create_time) { this.create_time = create_time; } public Date getUpdate_time() { return update_time; } public void setUpdate_time(Date update_time) { this.update_time = update_time; } @Override public int hashCode() { return id == null ? System.identityHashCode(this) : id.hashCode(); } @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass().getPackage() != obj.getClass().getPackage()) { return false; } final BaseEntity other = (BaseEntity) obj; if (id == null) { if (other.getId() != null) { return false; } } else if (!id.equals(other.getId())) { return false; } return true; } }
实体类
1 package a5_EmbeddedId; 2 import javax.persistence.AttributeOverride; 3 import javax.persistence.AttributeOverrides; 4 import javax.persistence.Column; 5 import javax.persistence.EmbeddedId; 6 import javax.persistence.Entity; 7 import javax.persistence.Id; 8 import org.hibernate.annotations.DynamicInsert; 9 import org.hibernate.annotations.DynamicUpdate; 10 11 @Entity 12 @DynamicInsert 13 @DynamicUpdate 14 public class Dog{ 15 /** 16 * 实体类 17 */ 18 private static final long serialVersionUID = -2776330321385582872L; 19 @Id 20 private DogPK pk; 21 22 private String mobile; 23 24 @EmbeddedId 25 @AttributeOverrides( { 26 @AttributeOverride(name = "dog_name", column = @Column(name = "dog_name")), 27 @AttributeOverride(name = "id_no", column = @Column(name = "id_no")) }) 28 public DogPK getPk() { 29 return pk; 30 } 31 public void setPk(DogPK pk) { 32 this.pk = pk; 33 } 34 public String getMobile() { 35 return mobile; 36 } 37 public void setMobile(String mobile) { 38 this.mobile = mobile; 39 } 40 }
组件类
1 package a5_EmbeddedId; 2 import java.io.Serializable; 3 import javax.persistence.Embeddable; 4 5 @Embeddable 6 public class DogPK implements Serializable { 7 8 /** 9 * 嵌入式组建 10 * 作为嵌入式主键类,要满足以下几点要求。 11 * 1.必须实现Serializable接口 12 * 必须有默认的public无参数的构造方法、必须覆盖equals 和hashCode方法,这些要求与使用复合主键的要求相同。 13 * 但发现没这么干也能跑,目前还未深入了解为什么 14 */ 15 private static final long serialVersionUID = -581520734909530534L; 16 17 private String dog_name; 18 private String id_no; 19 20 public String getDog_name() { 21 return dog_name; 22 } 23 24 public void setDog_name(String dog_name) { 25 this.dog_name = dog_name; 26 } 27 28 public String getId_no() { 29 return id_no; 30 } 31 32 public void setId_no(String id_no) { 33 this.id_no = id_no; 34 } 35 }
Dao
package daoUtil; import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; import org.hibernate.service.ServiceRegistryBuilder; public class HibernateUtil { private static final SessionFactory sessionFactory; static { try { Configuration cfg = new Configuration().configure(); ServiceRegistry serviceRegistry = new ServiceRegistryBuilder() .applySettings(cfg.getProperties()).buildServiceRegistry(); sessionFactory = cfg.buildSessionFactory(serviceRegistry); } catch (Throwable ex) { throw new ExceptionInInitializerError(ex); } } public static Session getSession() throws HibernateException { return sessionFactory.openSession(); } public static Object save(Object obj){ Session session = HibernateUtil.getSession(); Transaction tx = null; try { tx = session.beginTransaction(); session.save(obj); tx.commit(); } catch (RuntimeException e) { if (tx != null) { tx.rollback(); } throw e; } finally { session.close(); } return obj; } public static void delete(Class<?> clazz,String id){ Session session = HibernateUtil.getSession(); Transaction tx = null; try { tx = session.beginTransaction(); Object obj = session.get(clazz,id); session.delete(obj); tx.commit(); } catch (RuntimeException e) { if (tx != null) { tx.rollback(); } throw e; } finally { session.close(); } } }
main
1 package a5_EmbeddedId; 2 import daoUtil.HibernateUtil; 3 4 public class Test_EmbeddedId { 5 6 public static void main(String[] args) { 7 8 Dog dog = new Dog(); 9 DogPK pk = new DogPK(); 10 pk.setDog_name("wangcai"); 11 pk.setId_no("5"); 12 dog.setPk(pk); 13 dog.setMobile("13012345678"); 14 15 HibernateUtil.save(dog); 16 17 dog = (Dog)HibernateUtil.getSession().get(Dog.class, dog.getPk()); 18 System.out.println(dog.getPk().getId_no()); 19 } 20 }
环境:JDK1.6,MAVEN,tomcat,eclipse
源码地址:http://files.cnblogs.com/files/xiluhua/hibernate%40EmbeddedId.rar
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